GCSE EXAMINERS' REPORTS MATHEMATICS (NEW) NOVEMBER 2016 © WJEC CBAC Ltd. Grade boundary information for this subject is available on the WJEC public website at: https://www.wjecservices.co.uk/MarkToUMS/default.aspx?l=en Online results analysis WJEC provides information to examination centres via the WJEC secure website. This is restricted to centre staff only. Access is granted to centre staff by the Examinations Officer at the centre. Annual Statistical Report The annual Statistical Report (issued in the second half of the Autumn Term) gives overall outcomes of all examinations administered by WJEC. Unit Page Unit 1 - Foundation 1 Unit 1 - Intermediate 5 Unit 1 - Higher 8 Unit 2 - Foundation 12 Unit 2 - Intermediate 15 Unit 2 - Higher 18 © WJEC CBAC Ltd. MATHEMATICS (NEW) General Certificate of Secondary Education November 2016 UNIT 1 - FOUNDATION Given that this was the first time candidates have sat this paper, many made good attempts at many questions. However, there were some topics in the specification which appeared not to have been learnt by some candidates. Very many candidates did not attempt the question on rotational symmetry (Q8) or the question on location (Q10). It may be that many candidates were entered before they were ready to tackle the exam paper with confidence. The communication part of the OCW question (Q 4) was done reasonably well, though this is an area where more focused practice would be useful. This is one of the suite of Mathematics papers so the OC (organisation and communication) part expects a few words only, stating simply, for example, Length of side of square = 72 4 cm = 18 cm A long, rambling description is wrong in this Mathematics paper and will not gain credit. Clear, logical statements are expected. For the W (accuracy of writing) part, it is essential that the units are given appropriately and correct mathematical form is used. A statement like 72 4 = 18 3 = 54 is mathematically wrong and will not gain credit. 1. 2. (a) The curve proved more difficult to draw than the straight lines but there were many good attempts at drawing the reflection of the given shape. The reflection of the curve was expected to be within the equivalent set of squares as the original. This was not always the case. (b) A significant number of candidates did not attempt this question, and of those who did, very many measured the diameter of the circle rather than the radius. Despite being asked for the units that the candidate had used, many forgot to write them down. Common wrong answers included 90, 180 and particularly 360. (a) Almost all candidates attempted this question and very many gave the correct answer. Candidates needed to work out how many 5p coins Huw had, which was 6, so the correct answer was unlikely. The most common wrong answer was likely. (b) This was easier to answer as there weren’t any bananas in Catrin’s bag, so the chance of choosing one was impossible. © WJEC CBAC Ltd. 1 3. (a) This question was answered very well. (b) There were two possible correct answers: the numbers 1 and 13 or the numbers 2 and 5. The latter pair was far more common. This question was also answered very well. 4. More than a quarter of the candidates did not attempt this question. It might have helped those who felt they couldn’t engage with it, if they had drawn simple sketches of the shapes that the question described. This could have suggested to the candidates that they could find the length of one rod by dividing 72 by 4. Then, it would be straightforward to find the perimeter of the equilateral triangle. 5. Candidates were more likely to attempt part (b) rather than part (a). (a) A very common wrong answer was 100 as candidates subtracted 20 from 120, rather than correctly dividing 120 by 20. (b) Candidates seemed to find this part easier and were more successful with answering it. 6. Many candidates were unable to mark the position of A correctly; they were more successful with marking B correctly. The line given in the question was 10 cm long so marking every centimetre using their ruler should help candidates to show the position of A more accurately. Some placed A at 0 and B at 1, as if to label the line AB. Fortuitously, therefore, they gained the second mark. 7. Candidates needed to find how many 15s there are in 204. Most attempted to do this by adding a long list of 15s until they reached 210, showing them that 14 complete rows used 210 chairs. However, there were many slips in the addition. Very few tried a traditional, long division method. This might have been a more efficient method if the numbers had been different and the total number of chairs needed was much larger. 8. Very many candidates did not attempt this question or, if they did, were unable to answer it correctly. 9. (a) Wrong answers included 180, 360 and half turn. (b) Many ignored the fact that three of the triangles were coloured differently from the other three and this limited the order of rotational symmetry to 3. A frequent wrong answer was 6. (a) This was generally well done, though a significant number wrote down the correct coordinates (5, 4) in the reverse order (4, 5). (b) Again, many reversed the numbers in the coordinates so the plots were wrong and then it was impossible to draw a rectangle using the plotted points. (c) If the points in (b) had been plotted correctly, then usually the rectangle could be drawn. However, the coordinates of D could still be written wrongly in reverse. © WJEC CBAC Ltd. 2 10. Only about three-quarters of candidates attempted this question. Of those, very many marked P at the middle of the line AB. Others drew a line from B. Very many did not seem to understand what is meant by BAP. 11. Many candidates chose a number, apparently at random and with no connection to the numbers given in the question, and wrote that in the answer space without showing any working at all. Others thought that the angle on a straight line is 360 or 270 and subtracted the sum of 105 and 43 from that. 12. Altogether, this was a difficult question for very many candidates. More practice of basic arithmetic skills and better learning of appropriate rules would help most candidates. (a) Very common wrong answers were 28 (ignoring the correct position of the decimal point) and 1.1 (adding 04 and 07). (b) Very many did not set out the two decimals one above the other correctly and then they just subtracted digits randomly. (c) Very many wrongly thought that 33 is the same as 33 and that 24 is the same as 24. So a frequent wrong answer was 9 8 = 1. Another wrong answer was 1-1. (d) The correct answer was seen rarely. Most did not engage with using a common denominator at all but just gave the answer as 6/5. 13. This question was answered reasonably well. Candidates should be encouraged to use the space for working to test some values to work out the answers rather than guessing. 14. A common wrong answer was Blue 15 Yellow 10 Red 6. This obeys only two of the given conditions; i.e. B = Y + 5 and B + Y + R = 31 but not B = 4R. Many candidates were able to choose three values which added up to 31, but these values did not obey either of the other two conditions. 15. (a) This was answered very well. Even if they could not do the necessary calculation of subtracting 7, many candidates recognised that the next term in the sequence would be found by subtracting 7 from the previous number. (b) In contrast, this question proved to be beyond the capabilities of most candidates. Even if they realised that they needed to combine the x terms and separately combine the numbers, most candidates failed to equate these terms. If there was no equation, then neither of the first two marks could be awarded. Some candidates worked out that 4y = 32, but failed to go on to find the value of y. Many candidates wrote that 13y 5 is the same as 8y, and that 9y + 27 is the same as 36y and then stopped. © WJEC CBAC Ltd. 3 16. (a) This part was generally answered well though some did not follow the instruction to add the numbers on the two cards. (b) A large number of candidates did not seem to understand the phrase ‘more than 9’. So they included the 9 and wrongly gave the answer as 6/12 rather than 5/12. Many candidates did not understand the difference between chance and probability. The language of chance was not wanted. (c) Very many candidates were unable to work this out, certainly if they had given the answer to (b) as unlikely, say. The answer needed was 25, not 25/60. 17. This question was very challenging for very many candidates as there were three steps which had to be identified to find the solution. Some who were able to work out the length of CD as 15 9 = 6 cm were unable to use this as they could not work out the length of BD by dividing 45 by 9. Not all who got this far remembered the correct formula for the area of a triangle. Many added up random numbers, apparently trying to find a perimeter. 18. This question was answered well by many candidates, especially those who tried out pairs of numbers. 19. Not all the numbers given as answers lay between 1 and 9 inclusive. A frequent mistake was writing 6 in the middle box, thinking that that would make it the median, whatever other numbers were chosen. Realising that the total of the five numbers needed to be 25 to give the mean as 5, made the question easier to answer. © WJEC CBAC Ltd. 4 MATHEMATICS (NEW) General Certificate of Secondary Education November 2016 UNIT 1 - INTERMEDIATE This was the first time that candidates sat the new Mathematics GCSE specification. It appears that perhaps some of the candidates may not have been entered appropriately for this tier. A larger than usual number of candidates did not attempt some questions which suggests that they had not yet fully covered the course at the time of the examination. Hopefully they will have a greater degree of understanding by the summer series of exams. 1. (a) The usual error was the misplacement of the decimal point. Worryingly a number of candidates used the ‘herringbone’ method of multiplication for essentially multiplying 4 by 7 0 4 0 7 etc. (b) Well answered. (c) Most candidates gave the correct answer of 11. Some thought 33 – 24 equated to 9 – 8 = 1. (d) A few gave the common incorrect answer of 6/5. Most candidates correctly used a common denominator of 10. Some correctly used a common denominator of 50. 2. A mixture of responses with no one particular statement being consistently misunderstood. 3. There were more correct answers of ‘Blue = 16, Yellow = 11 and Red = 4’ seen than incorrect combinations. Most candidates were able to satisfy at least two of the conditions. 4. (a) Well answered. (b) The −2f was often given as −8f. (c) A correct embedded answer was accepted but candidates should be made aware that the actual answer has to be seen before a mark is awarded e.g. 22 = 4 + 3 × 6 is enough to imply that K = 6, but 22 = 4 + 18 alone, would not gain any marks. © WJEC CBAC Ltd. 5 5. (a) The table of scores was usually completed correctly. (b) Most of the candidates knew how to present a probability as a fraction. There was however a high degree of misunderstanding over what was meant by ‘more than 9’. Several candidates included the 9 from their table to give an answer of 6/12 rather than 5/12. (c) An answer of ‘25’ was required and not ‘25/60’. 6. Candidates should be made aware of what is taken into consideration when awarding the OC and W mark. Responses should be structured with explanations that are clear and logical to the reader at the point in the solution when they are presented (not a series of calculations followed at the bottom of the page with a detailed explanation). Correct mathematical form is required. Units, where appropriate, should be shown. We do not want to see, for example, ‘Area of a triangle = 6 × 5 = 30/2 = 15’. Those candidates familiar with the area of simple shapes found the actual question accessible. 7. Correctly placed embedded answers were allowed in all three parts of this question. It is not however a practice that should be encouraged as often the candidate shows further work which is not mathematically correct. (a) Well answered with 2 being the popular wrong answer. (b) Well answered with 294 being the popular wrong answer. (c) An error was often seen on the right hand side of the first line of solutions with 4y = 22 given instead of 4y = 32. 8. Well answered. 9. The condition most often not met was that the numbers should have a median value of 6. Many candidates placed a 6 in the middle box thinking this alone would make 6 the median value. Of the four possible fully correct combination of numbers, the choice of 1, 3, 6, 7 and 8 was by far the one most candidates opted for. 10. (a) A fairly straight forward question that was not well answered. Many thought that the sum of the exterior angles of a polygon totaled 180° and gave an answer of 4 sides. It would be interesting to challenge those who gave an answer of 2 to draw us their ‘polygon’! (b) Very few candidates constructed accurate drawings using only a ruler and a pair of compasses. There was little evidence of ‘fake arcs’ but more a case of random arcs drawn from random centres. © WJEC CBAC Ltd. 6 11. 12. 13. (a) Calculating the correct value for y when substituting into the quadratic proved difficult for many of the candidates. (b) There was evidence of misreading of the scale on the y-axis when attempting to plot their coordinates. Candidates should take care to draw a smooth curve passing through (not just in the vicinity) all of their plotted points. (c) The negative value of one of the points of interception was sometimes overlooked, resulting in an unnecessary loss of a mark. (d) Very few chose the correct equation. (a) The popular incorrect choice was 8. Presumably candidates thought ‘six sides and two faces, so 8 outcomes’. (b) The mark scheme allowed for a follow through answer from part (a). So those who gave an answer of 8 in (a) were given a mark for 1/8 in (b) (c) A mixture of responses with no one particular incorrect choice being made. (a) Not the most difficult of formula to work with, but still poorly answered. (b) Candidates often gave only a partial factorisation. 14. (a)/(b) A similar type of question was included in the Specimen Assessment Materials produced prior to this examination. It was disappointing therefore that so few correct answers were given to these two questions. 15. This question tested the candidates’ ability to form and solve two simultaneous linear equations. It was also one of the questions that addressed Assessment Objective 3 (AO3) in that candidates had to, ‘interpret and analyse the problem before generating a strategy to solve it’. A ‘trial and improvement’ method is not acceptable when solving simultaneous equations. 16. (a) A similar type of question was included in the Specimen Assessment Materials produced prior to this examination. It was disappointing therefore that so few correct answers were given. Most candidates assumed that the branches regarding ‘stopping for a break’ were to be labelled 0·42, 0·58, 0·42 and 0·58. (b) A follow through answer using their values for P(Hereford) × P(No) was allowed. Unfortunately not many candidates seemed to be familiar with the required rule. 17. There was a requirement in the question for an inequality to be written down. Candidates who failed to do so would not gain all of the marks available. © WJEC CBAC Ltd. 7 MATHEMATICS (NEW) General Certificate of Secondary Education November 2016 UNIT 1 - HIGHER This was the first time that candidates had sat the new Mathematics GCSE specification. As expected, pupils’ performances reflected the increased demand of later questions in the paper. The majority of candidates attempted every question, and coped well with the variety of both content and style of question; this suggests that they had mostly been entered for the appropriate tier, though there were a number of exceptions to this. Whilst there were plenty of excellent performances, there were also some particular areas in need of attention: Question 2(a)(b) - recognising that the graph of a quadratic function should be a smooth parabola, and that calculated coordinate values should be revisited if this is not the case; Question 2(d) - understanding that the intersection of two graphs represents the solution of an algebraic equation, and knowing how that equation may be obtained; Question 3(b) - knowledge of standard construction methods using ruler and compasses; Question 5 - manipulating numbers in standard form; Question 13 - recognising when to apply specific circle theorems and quoting them formally; Question 15(b) - sketching simple transformations of graphs of trigonometric functions; Question 16 - knowledge of the conditions required to prove the congruence of triangles, and applying them within a formal proof; Question 17 - manipulating surds. 1. Most candidates answered this question well, however some incorrectly gave 8 as their answer to part (a) (presumably from adding six sides and two faces rather than considering the outcomes of the compound event). For part (b), the mark scheme allowed for a ‘follow through’ answer from part (a). Many gave the correct answer for part (c), and of those who were successful, most employed a written method (either multiplying probabilities or constructing a two-way table). 2. There were many excellent responses to parts (a) to (c) of this question. However, for part (a), some candidates did struggle to calculate the required coordinate values, particularly when needing to square minus 1. For part (b), most plotted all the points correctly, coping well with the different scales on the axes and going on to draw a smooth parabola. (A minority were penalised for joining their points with straight lines rather than drawing a curve.) When the values in part (a) were incorrect to the extent that the shape of the graph was not even close to the correct parabola shape, it was disappointing that candidates did not seem to question this and revisit their initial calculations. The majority were successful in part (c), though occasionally the negative value was mis-read as being on the ‘wrong side’ of minus 1. © WJEC CBAC Ltd. 8 Part (d) was disappointing. A very small minority demonstrated understanding by equating the quadratic expression to 5 and re-arranging in order to select the correct equation. 3. 4. (a) Well answered, with almost all candidates knowing to divide 45 into 360. Some used an unnecessarily lengthy (though still valid) method of considering the total of the interior angles. (b) Many candidates did know how to use a ruler and pair of compasses for a construction, however there was some evidence of ‘fixing’ (drawing fake arcs). More appeared to know how to bisect an angle than knew how to draw the initial perpendicular line (appearing to draw the latter by eye or by using a protractor). (a) Well-answered, but for the occasional sign error. (b) Again, well-answered, but for a minority of partially factorised answers. 5. Both parts (a) and (b) were usually well-answered, though some failed to observe the instruction to express the answers in standard form. In part (b), too many candidates unfortunately gave no consideration to place value, simply adding 2·3 and 6·4. Also, the powers of 10 were often added here, indicating confusion between methods for adding or multiplying. 6. Many excellent solutions were seen for this question. Candidates recognised the need to set up and solve a pair of simultaneous equations, often going on to do so successfully. (However, one unexpected error in a significant minority of cases was evaluating 10/4 to be 0·4 for the value of y.) Though rarely seen, it is worth noting that use of a trial and improvement method was not acceptable in this question. For the OCW requirement of the question, the majority of candidates performed well, though some needed to engage with the need to ‘communicate’ by explaining where each of their equations had come from. (This could have been done by simply labelling the equations as ‘square’ and ‘octagon’.) The quality of written algebra was good in most cases, as was the arithmetic involved in calculating the second variable. 7. There were plenty of excellent solutions seen for both parts of this question. In part (a), however, it was a concern that a great many candidates did not attempt to unpick the probability of the compound event (by appropriately dividing 0·42 by 0·7), opting to write 0·42 on the P(Yes) branch of the tree diagram instead. For part (b), candidates usually knew to multiply the relevant probabilities (and were allowed to follow through their answer from part (a)). 8. Plenty of fully correct solutions were seen here, but too many failed to write down an inequality (a requirement given in the question). 9. Both parts were usually well-answered. Again, it is worth noting that those candidates who wrote down a method appeared to be most successful. © WJEC CBAC Ltd. 9 10. This question proved difficult for the majority of candidates. Many were able to deduce the need to equate the volume of a hemisphere and the volume of a cone, and were often able to do so correctly. Few, however, were able to progress correctly to a simplified relationship between the common radius and the height of the cone. Fewer again succeeded in meaningfully producing a final ratio. Since the relevant formulae (for the volume of a sphere and volume of a cone) were both printed in the formula list at the start of the paper, it was disappointing that these were sometimes quoted with incorrect powers of r. 11. Many candidates gained full marks in this question. For part (a), however, some showed lack of understanding of ‘inverse’ proportionality, answering as if it were direct proportion. (Others answered as if y was inversely proportional to x2 rather than x, indicating a need for more careful reading of the question). In part (b), most knew what to do, though some had difficulty in dealing with the given y value of 1/5. 12. It was encouraging to observe some secure algebraic skills here, though there was often a sign error in the last term of the numerator. Weaker candidates were unable to begin to form a common denominator. 13. Candidates were often successful in applying the alternate segment theorem (though it was sometimes incorrectly quoted as ‘alternate angles’), and were then usually able to progress to finding a correct expression for angle PQR. The main weakness in this question was a reluctance to formally or adequately quote relevant circle theorems. It was also of concern that a few candidates misinterpreted lines PQ and AB as if they were parallel, suggesting that angles PQR and BRQ were equal. Candidates should be encouraged to simplify their final answer, rather than leaving it as e.g. 180 – 90 – x. 14. In part (a), it was necessary to derive the quadratic equation shown. Many convincing solutions were seen, but those who could not approach it opted to solve the equation instead (though this was not required until part (b)). For part (b), the majority of candidates were able to factorise the quadratic expression and give two solutions, usually explaining correctly that the negative solution could not represent a length. A minority used the quadratic formula – a more laborious but still acceptable method. Again, trial and improvement should be discouraged as a method to solve a quadratic equation. Some candidates misunderstood the requirement in part (b) to ‘justify any decisions’, interpreting this as a need to construct the equation (already done in part (a)) or as a need to substitute answers into the equation to verify them. 15. Part (a) was usually well-answered, but for part (b), too many candidates simply sketched the graph of y = cos x, disregarding the need for a vertical translation of 1 unit. 16. Overall, this was very disappointing. Candidates needed to use the information given in the question to prove congruence of the triangles (rather than using the symmetry of the diagram to deduce equal lengths or angles). Many solutions lacked rigour and necessary justification e.g. stating that AB = AC without explaining why (namely that the triangle was stated to be isosceles). It is important to note that stating ‘two sides and an angle’ is not an adequate reason for concluding that triangles are congruent unless it is made clear that the angle is ‘included’ (which may be implied by quoting ‘SAS’). © WJEC CBAC Ltd. 10 17. Fluent manipulation of surds was essential in this question. There were some excellent solutions. Common errors however included misinterpreting (5√3)2 to be (5 + √3)2 or giving 2√18 to be √36. It was surprising that some candidates stated a final rational fraction to be ‘irrational’. 18. This was often well-answered, with many candidates choosing to construct an appropriate tree diagram. Of those who did not proceed correctly, some tried to state that 0·8 x 0·8 was 0·16 in order to then multiply by 5. © WJEC CBAC Ltd. 11 MATHEMATICS (NEW) General Certificate of Secondary Education November 2016 UNIT 2 - FOUNDATION This was the first time that candidates sat the new Mathematics GCSE specification. It appears that the majority of candidates who were entered were working at F/G grade. A large number of candidates did not attempt the intermediate crossover questions which suggests that they had not yet fully covered the course at the time of the examination. Hopefully they will have a greater degree of understanding by the summer series of exams. 1. (a) This part was generally well answered – common errors were putting the decimal point in the wrong place or omitting it altogether. (b) This part was generally well answered, though a common incorrect answer was 109.9, where candidates ignored the final value was in pence not pounds. Both rounding parts were well answered. 2. This question was not well answered by candidates. As it’s a true and false question you’re unable to fully understand the candidates reasoning for their selections, though it was clear that they were confusing pentagons and hexagons, diameters and radii, and the names of triangles. 3. Candidates should be made aware of what is taken into consideration when awarding the OC and W mark. Responses should be structured with explanations that are clear and logical to the reader at the point in the solution when they are presented (not a series of calculations followed at the bottom of the page with a detailed explanation). This question was not well answered by candidates. Candidates who engaged with the question were generally able to identify the factors of 20, though they often struggled to fulfil the other conditions - identifying the factors which sum to greater than 10 but less than 15. 4. This question was answered well by over half of the candidates. Incorrect answers were usually as a result of candidates confusing mode, median and mean. 5. (a) This part was well answered by over half of the candidates. The most common incorrect answer was 9a. (b) This part was answered slightly better, though some candidates failed to gain the second mark for identifying the rule – writing “plus 4” was the common incorrect answer. 6. This question wasn’t answered well. Many candidates were able to find one of the extra values (nearly always 17), but not the second value (1) – gaining two out of the three marks. © WJEC CBAC Ltd. 12 7. 8. 9. (a) Some candidates were able to list all of the possible outcomes in part (i), with some able to calculate the probability in part (ii). Common incorrect answers were just listing the outcomes involving Heads, totally ignoring those involving Tails. This prevented them from gaining any marks in (ii) because candidates needed at least 4 additional outcomes in part (i) to gain any marks in (ii). (b) This part wasn’t well answered, with candidates commonly stating that both outcomes had an even (as opposed to equal) chance of occurring. Overall this question wasn’t well answered by candidates. (a) 57 was a common incorrect answer. (b) 43 was not accepted unless 64 was also shown. (c) 186 ÷ 3 was not accepted unless 62 was also shown. (d) 7·25 × 8 was not accepted unless 58 was also shown. (a) This part wasn’t answered well by candidates, with the most common incorrect answers being 120° and 60°. (b) This was answered considerably better than part (a). 10. This question was poorly answered by candidates. Reflecting the shapes in the horizontal line was a very common error. 11. This question was poorly answered by candidates - most simply calculated 360 – (117 + 74 + 125) and gained no marks as the ‘125°’ was the only value that was not allowed as a follow through of what should have been 55°. 12. (a) A correctly placed embedded answer was allowed. It is not however a practice that should be encouraged as often the candidate shows further work which is not mathematically correct. (b) Some candidates mistook the process involved in a number machine with that of the hierarchy of number operations by writing −2 + 5 × 7 = 33. (c) This part was answered poorly – most candidates didn’t attempt this part, with those that attempted it often answering 2x + 3. 13. This question was poorly answered. Very few candidates gained full marks, with many stating it was true with no or little (normally incorrect) calculations. Some candidates gained 2 marks for increasing by 10% but were unable to correctly decrease by 10%. 14. This question was poorly answered. Whilst the candidates can recognize congruent shapes and are familiar with simple 2-D shapes, they obviously found it difficult to visualise the shapes and relate the statements to the concept of congruency. 15. This question was well answered, though some candidates thought that the missing value for Newport was 0°C. © WJEC CBAC Ltd. 13 16. Those candidates familiar with the formula for the circumference of a circle found the actual question accessible, however they were few and far between, with some using the formula for area, whilst others not being able to progress further than calculating the diameter of the circle. 17. (a) Very poorly answered – most candidates simply reflected in the x or y-axis. (b) This part was poorly answered. The question asked for the description of a single transformation. Those descriptions indicating more than one step (the ‘and then’) gained no marks. All four components were required (anticlockwise rotation of 90° about the origin). Obviously a ‘clockwise rotation of 270°’ would be equivalent. Allowances were made as regards the description of ‘the origin’ but the word ‘turn’ was not accepted for ‘rotation’. Very few candidates identified all four components (most identified only two) the component most often left out was ‘about the origin’. © WJEC CBAC Ltd. 14 MATHEMATICS (NEW) General Certificate of Secondary Education November 2016 UNIT 2 - INTERMEDIATE This was the first time that candidates sat the new Mathematics GCSE specification. It appears that perhaps some of the candidates would have been better suited if they had been entered at a different tier. A larger than usual number of candidates did not attempt some questions which suggests that they had not yet fully covered the course at the time of the examination. Hopefully they will have a greater degree of understanding by the summer series of exams. 1. 2. All parts of this question were well answered. (a) 57 was a common incorrect answer. (b) 43 was not accepted unless 64 was also shown. (c) 186 ÷ 3 was not accepted unless 62 was also shown. (d) 7·25 × 8 was not accepted unless 58 was also shown. (a) There were nearly as many answers of 120° or 60° as there were of the correct 30°. (b) Very well answered. (c) Well answered although a significant number chose 90°, presumably having turned anticlockwise. 3. Reflecting the shapes in the horizontal line was a very common error. 4. (a) A correctly placed embedded answer was allowed. It is not however a practice that should be encouraged as often the candidate shows further work which is not mathematically correct. (b) (i) Several candidates mistook the process involved in a number machine with that of the hierarchy of number operations by writing −2 + 5 × 7 = 33. (ii) The most frequent error was to omit brackets around the n + 5. A few are uncomfortable with leaving an expression as an expression, but continue to solve an imaginary equation. 5. Well answered although a number of candidates thought that the missing value for Newport was 0°C. © WJEC CBAC Ltd. 15 6. The weaker candidates simply calculated 360 – (117 + 74 + 125) and gained no marks as the ‘125°’was the only value that was not allowed as a follow through of what should have been 55°. 7. Well explained and clear reasoning shown with accurate calculations to prove that the statement was incorrect. Some chose ‘interesting’ start values. ‘87·6 × 1·1 = 96·36 followed by 96·36 × 0·9 = 86·724 so false’ is one that sticks in the mind! 8. Many of the candidates failed to choose the correct response to each of the four statements. Whilst at a lower level of testing they can recognize congruent shapes and are familiar with simple 2-D shapes, they obviously found it difficult to visualise the shapes and relate the statements to the concept of congruency. 9. Candidates should be made aware of what is taken into consideration when awarding the OC and W mark. Responses should be structured with explanations that are clear and logical to the reader at the point in the solution when they are presented (not a series of calculations followed at the bottom of the page with a detailed explanation). Correct mathematical form is required. Units, where appropriate, should be shown. We do not want to see, for example, ‘Circumference = π × 40 = 125·6 ÷ 2 = 62·8’. Those candidates familiar with the formula for the circumference of a circle found the actual question accessible. 10. (a) Common incorrect answers were ‘n + 1’ and ‘3n + 1’. (b) (i) Not as well answered as expected at this level. There was no obvious consistent misunderstanding shown by the answers given. (ii) Initially converting the problem into an inequality ‘n2 + 7 > 85’ would have very much simplified the question. Unfortunately very few began their solution with this initial step. 11. (a) A disappointing response to a relatively straightforward question on reflection. There was no obvious consistent misunderstanding shown by the answers given. (b) The question asked for the description of a single transformation. Those descriptions indicating more than one step (the ‘and then’) gained no marks. All four components were required (anticlockwise rotation of 90° about the origin). Obviously a ‘clockwise rotation of 270°’ would be equivalent. Allowances were made as regards the description of ‘the origin’ but the word ‘turn’ was not accepted for ‘rotation’. The component most often left out was ‘about the origin’. (c) (i)/(ii) A similar type of question was included in the Specimen Assessment Materials produced prior to this examination. It was disappointing therefore that so few correct answers were given to these two questions. Candidates need to be aware that a column vector requires the brackets to be in place and that a ‘fraction’ e.g. 5/4 is not acceptable. © WJEC CBAC Ltd. 16 12. (a) Common incorrect answer was x18. (b) Common incorrect answer was (4x – 3y). (c) By far the answer given by most candidates was x/30. Often accompanied by an explanation that ‘speed = distance / time’! 13. Those candidates familiar with this type of question usually gained all four marks. Some did not carry out the necessary check required (e.g. looking at 2·25) to establish that the answer was 2·3 and not 2·2 and therefore only gained two marks. 14. (a) Well answered although a number of candidates decided that the extra 4 students required in the Chemistry set should go alongside the 1, 2 or 6 already shown in the Venn diagram. (b) Many gave the incorrect answer of 8, having wrongly included the six students who studied all three subjects. (c) Well answered. 15. This topic was not well understood. (a) (b) 16. (i) Few knew how to find the gradient, and some of those who did know, misread the (different) scaling on the two axes. (ii) The instruction to write the equation of the line in the form y = mx + c was ignored by many of the candidates. Despite the mark scheme generously trying to give some credit for any understanding of gradients of equations and the connection with parallel lines, very few gained marks on this part of the question. Another topic not well understood. (a) More often than not, the answer given was simply 0·05. (b) Little of what was written made any sense! Many focused on the greater number of defective sockets there were, rather than the best estimate of the probability of selecting at random a defective socket. 17. It was one of the questions that addressed Assessment Objective 3 (AO3) in that candidates had to, ‘interpret and analyse the problem before generating a strategy to solve it’. Many having correctly identified angle BDC = 28° and angle BCD = 90°, then used an incorrect trig ratio when attempting to calculate the length of BD. This was probably because line CD was a ‘sloping line’ and of course for some ‘the hypotenuse is the sloping line’! 18. (a) A standard question that was poorly answered. It was disappointing to see so many attempting to use a ‘trial and improvement’ method. (b) A similar type of question was included in the Specimen Assessment Materials produced prior to this examination. It was disappointing therefore that so few correct solutions were seen. © WJEC CBAC Ltd. 17 MATHEMATICS (NEW) General Certificate of Secondary Education November 2016 UNIT 2 - HIGHER This was the first time that candidates had sat this paper. However, it appeared that most candidates did attempt most questions, although it was evident that some of their subject knowledge was lacking towards the end of the paper. Candidates still need to be reminded to show their workings, even when not directed to do so within the question. 1. (a) Not answered as well as expected for the first question. The majority of candidates could draw the line 𝑦 = 𝑥, but failed to reflect the triangle correctly. A common mistake was a rotation of 180° about the vertex that touches the reflection line, ie. 𝑦 = 𝑥. Occasionally the triangle was reflected on the 𝑥-axis even though 𝑦 = 𝑥 was correctly drawn. (b) (i) Occasionally the error here was incorrectly assigning the column vector numbers with the 𝑥 direction and the 𝑦 direction. (ii) Generally well answered, although not all candidates were conversant with the column vector form – either giving their answers incorrectly in the form of a fraction (with or without brackets) or as coordinates. 2. Well answered on the whole, with some slips in working from time to time. 3. (a) Well answered. Occasionally, the incorrect answer seen was 𝑥 18 . (b) The misconception many candidates made was incorrectly expanding the second bracket, i.e. −(3𝑥 + 2𝑦) expanded to −3𝑥 + 2𝑦 (instead of the correct −3𝑥 − 2𝑦) leading to the incorrect answer of 4𝑥 − 3𝑦. (c) This part was not as well answered, with 30 being the most popular answer. Candidates had failed to see the need to convert the minutes into hours. 𝑥 4. The majority of candidates answered this question well, with a significant number gaining full marks. Apart from the obvious error of not testing to find the answer correct to 1 decimal place (usually by trialling x = 2.25), other slips seen was not finding values correct to 1 dp either side of 0, or not using the given formula correctly. 5. Although Venn diagrams is a new topic, candidates answered this question well. (a) Generally full marks were awarded. The occasional error was placing the 4 in the wrong region, usually in the area specific to chemistry. (b) The incorrect answer of 8, presumably by adding 5, 2 and 1 together of the top regions was occasionally seen. (c) Very well answered. However many candidates did superfluous work; simplifying the fraction even though it was not required. © WJEC CBAC Ltd. 18 6. 7. 8. (a) (i) The different scale on each of the axes contributed to the failure of a number of candidates on this part of the question, the gradient of 1 being a common answer. Some candidates failed to appreciate that it is only the coefficient which is the gradient, resulting in 2𝑥 being offered rather than 2. (ii) Reasonably well answered. Most candidates followed through their gradient correctly, and generally, the 𝑚 and the 𝑐 were not incorrectly interchanged. Infrequently the ‘𝑦 =’ was omitted. (b) This was one of the first questions on the paper which was poorly answered. Although many were able to either double or halve one of the given equations (although many candidates only focussed on the 𝑥 and 𝑦 coefficients and forgot to halve or double the constant term), they were unable to justify why the lines were parallel. They needed to be able to explain why the gradients would be the same – showing an understanding, that was often lacking. Those candidates who correctly rearranged the equations to the form y = mx + c were able to gain both marks, if they commented on the equal gradients or not. (a) This question was not as well answered as expected, with many candidates not offering the correct method and answer. Many candidates only offered the relative frequency for 3000 sockets tested, whilst others offered a sum of the defective sockets for 1000, 2000 and 3000, amongst other answers. A number of candidates incorrectly read the relative frequency for 3000 as 0.5. Also, some candidates just wrote down 0.05 as their answer. (b) More candidates knew that the best estimate would be gained from reading from the graph at 5000 sockets tested – the greatest number tested. The probability was often given as a fraction 240/5000, although only the reading of the relative frequency at 5000 was required. The OCW question in this paper. ̂ C and furthermore A considerable number of candidates could evaluate angle B𝐷 BĈD correctly quoting the circle theorems. Of these candidates many then did realise that trigonometry should be employed but some candidates used the incorrect ratio because they labelled the sides incorrectly (tan 28° was often seen as an error). Some candidates also correctly used the sine rule to work out side BD. Another error 4.7 was incorrectly solving, sin 28 = 𝐵𝐷, i.e. the unknown as the denominator of the equation. Focussing on the OCW marks, many candidates did not write down the fact that B𝐶̂ D = 90°, although they may have shown it on the diagram, or implied it within their working (by correct use of trigonometry) – they often lost the mark for the Writing element within the OCW marks in this case. In the OC element of the OCW marks, candidates were expected to present their working in a structured way, explaining each step of their answer. Unfortunately, a number of candidates are still writing a short account of their process, writing it separately from their calculations. For the W element, apart from not stating B𝐶̂ D = 90°, candidates also need to remember to use correct mathematical form, and to include the units in their working and answers (° and cm here). © WJEC CBAC Ltd. 19 9. (a) This question was well answered, especially the follow through to give the values for 𝑥 from the candidates’ brackets whether it was correctly factorised or not. Incorrect signs in the brackets was the common error seen in the factorising. (b) A fair number of candidates gained full marks. Generally the marks lost were from errors in expanding after the denominators were changed to be common in all the terms. For example (7𝑥 + 1) incorrectly doubled to 14𝑥 + 1 was often seen. Once the equation was simplified to have no denominators a number of candidates made arithmetical errors with directed numbers or incorrectly rearranged the equation to solve for 𝑥. Also the numerator being multiplied by its respective denominator was seen on occasion. 10. This question was not answered particularly well. There were numerous errors seen within the scripts, ranging from using a positive enlargement (sometimes fractional), a negative enlargement using the incorrect scale factor, or using the incorrect centre of enlargement. Many candidates made more than one of these errors gaining few, if any, marks. 11. This question was very well answered. The only occasional error was multiplying a lower bound by an upper bound. 12. (a) Not well answered. Candidates did not realise that they could factorise the brackets (x – 7) leading to a simple and elegant solution. Many candidates expanded the brackets, and collected the terms, before factorising to give the required answer. However, many slips were seen when employing this method leading to scoring either 1 or no marks. It was surprising that many candidates who expanded the expression correctly, i.e. 𝑥 2 − 12𝑥 + 35, did not proceed to factorise it, this being a relatively simple B grade question with the 𝑥 2 coefficient equalling 1. (b) Again, this question was poorly answered. The majority of candidates who did gain any marks here gained only the first mark for 3(4x2 – 9y2). Few were able to go further, although some other partial factorisations were also seen e.g. (2x – 3y)(6x + 9y). 13. The majority of candidates gained the first mark for expanding the single brackets correctly. From there onwards numerous, fundamental errors were made showing a clear lack of understanding of the process involved of collecting subject terms on one side, factorising and then dividing. Numerous candidates would (incorrectly) divide the equation by each 𝑥 term coefficient, not appreciating that this process would affect all terms. Surprisingly at this level, signs of terms were not inverted correctly when collecting on one side of the equation. 14. (a) Most candidates found it difficult to get started on this question, due to having to work back from knowing the area of the sector to find the angle at the centre. A few were able to start by calculating the area of the complete circle 𝜃 65 and then stating that = . If they got as far as this, they were often 360 𝜋×102 able to go on to find the required angle. © WJEC CBAC Ltd. 20 (b) This part of the question was often left unattempted, especially if they had had difficulty in (a). Those candidates who gained all 3 marks in (a) usually gained both marks in (b). A few candidates, who had got an incorrect answer in part (a), were, however, also able to go on to gain these 2 marks for the arc length, bearing in mind that an incorrect angle could be used as a follow through. 15. This question was not well answered, with no pattern to the answers offered. It would be beneficial to candidates, and schools, to not only concentrate on the shape of different graphs, but also on recognising the intercepts of equations of different graphs on each of the x and y axes. 16. Many unforeseen errors were made by the majority of candidates whilst expanding the expressions on either side of this equation, meaning that they normally gained one of the three marks available for setting up the equation in the form 𝑎𝑥 2 + 𝑏𝑥 + 𝑐 = 0. For their equation, many candidates made slips in substituting −𝑏±√𝑏2 −4𝑎𝑐 their values of a, b and c into , which meant that only M1 was available. A 2𝑎 common error was incorrectly evaluating the 𝑏 2 in the discriminant to be negative when 𝑏 is itself negative. A number of candidates failed to duplicate the formula correctly, even though it is given on the Formula list, within the front cover, meaning they lost the last three marks. 17. This question, when attempted, seemed to gain candidates either no marks or full marks. If they knew to find the linear scale factor, from stating, or calculating, the ratio of the areas, then they usually went on to find the perimeter of the larger shape correctly. The remaining candidates simply wrote that the scale factor to be 700/140 = 5, without considering this to be ratio of the areas – they gained no marks. 18. (a) This question on the whole was not answered well, even though the majority of candidates attempted the question. The important step of needing to find the angle within the triangle, at the centre of the star, was imperative, and the majority of candidates failed to recognise this. Instead, the majority of candidates incorrectly imagined that each triangle was right-angled, and immediately lost all marks for part (a). However, a fair number of students gained some marks for correctly using the cosine rule with their derived angle. An error made by a number of candidates who did employ the cosine rule was the failure to appreciate the order of operations in the calculation. They calculated 𝑏 2 + 𝑐 2 correctly to be 149, but then proceeded to subtract 2𝑏𝑐 (equalling 140) before multiplying by the cosine of their angle. (b) Had the candidates found an angle, correct or otherwise, at the centre of the star, then a significant number of candidates were able to gain marks here for 1 employing A = 2ab sin C . On the other hand, those candidates who had imagined the triangle to be right-angled in (a), continued to do so in (b), and again lost the marks. © WJEC CBAC Ltd. 21 WJEC 245 Western Avenue Cardiff CF5 2YX Tel No 029 2026 5000 Fax 029 2057 5994 E-mail: [email protected] website: www.wjec.co.uk © WJEC CBAC Ltd.
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