Easter School
Maths Literacy
Ratio, Rate & Proportion I
Grade 12
24 March 2013
Key Concepts
In this session, we will focus on summarising what you need to know about:
 Ratio and proportion
 Rate, including exchange rate
Terminology & definitions
A Concept: Ratio & Proportion
• A ratio involves comparing two quantities of the same units.
• A ratio can be written in many equivalent forms, e.g., 1:2 = 5:10 = 25:50
• Ratios can also be written as fractions, decimals or percentages,
e.g., 1:2 = ½ = 0,5 = 50%
• Proportion is a ratio or fraction, and can also be described as a quantity compared to
another quantity.
X-ample 1
A bottle of concentrated orange juice has to be diluted with water in order for it to be
drinkable. The label on the bottle tells you to dilute the orange juice with water so that
the ratio of concentrate to water is 1:3.
a) How many litres of drinkable orange juice will you be able to make from a 500ml
bottle of concentrate?
b) In order to make 3L of drinkable juice, how many ml of concentrated orange juice
will be required?
X-ample 2
R30000 is divided between Thandi & Crystal in the ratio of 2:1. How much does each
person get?
X-ample 3
In a school with 300 students, 180 are girls and the rest are boys.
a) What is the ratio of girls to boys?
b) What proportion of the school do the boys make up?
c) If 100 students walk to school and the rest take a bus
1) What proportion of the students take a bus?
2) What is the ratio of students that walk, to students that take a bus?
www.learnxtra.co.za
Follow us on Facebook: www.facebook.com/learnxtra
Contact us at: [email protected]
Page 1
Easter School
Maths Literacy
Ratio, Rate & Proportion I
Grade 12
24 March 2013
mindset.co.za/learn Contact us at: [email protected] Page 2 B Concept: Rate
• When one quantity changes with respect to another.
Exchange Rates
• Different countries use different currencies (or forms of money). The exchange rate is
used to convert from one currency to another.
• Exchange rates change continuously.
• If the exchange rate states $1 = R8, this means that one US dollar will cost you R8.
X-ample 4
On a certain day HK$ 1 = R0.925426, using an Internet site, you decide to buy a special
DVD set that costs HK$ 270. How much will you have to pay in rands?
X-ample 5
Carl has returned to SA from a trip to the US and finds that he still has $200 that he did
not spend. He wants to convert the dollars back into rands.
1) If the exchange rate at the time is $1 = R7,45, how many rands will he get?
2) If he waits for a month, the new exchange rate will be $1 = R7,05
a) Will he get more or less rands if he waits?
b) How much will he get if he waits for a month?
X-ercise
1. If a map has a scale of 1:50 000, this means that 1cm on the map represents
50 000cm on the ground. You measure the distance between two points on the map and
find that it is 6,25cm. What is the actual distance, in km, using the given scale between
these two points on the ground?
2. The exchange rates on a specific day are:
$1 = R7,23 €1 = $1,31 £ 1 = R 13, 6189
a) Convert € 200 to US dollars
b) Convert R5000 into US dollars
c) Convert 500 pounds to rands.
3 The exchange rate is: $1 = R7,39
a) If I buy a computer from the US that costs R5500, how many dollars will I be paying?
b) If I have to add on a 12% delivery charge, how much in rands must I now pay?
4. Four students rent a flat together and share the rent of R5300 equally. A maintenance
levy of R492 is also charged per month.
a) What is the ratio of each of the student’s share of rent?
b) Calculate the total rent (including the levy) that each person must pay per month.
c) Work out the maintenance levy as a percentage of the total rent paid.
d) If the rent increased to R5650 per month at the end of the year, calculate the
percentage increase in rent.
www.learnxtra.co.za
Follow us on Facebook: www.facebook.com/learnxtra
Contact us at: [email protected]
Page 2
Easter School
Maths Literacy
Ratio, Rate & Proportion I
Grade 12
24 March 2013
X-ercise Answers
1. Scale 1 : 50 000
So 6,25cm: 50 000 X 6, 25 (multiply both numbers by 6,25)
6,25cm : 312500 cm
6,25 cm represents 312 500 cm = 3,125 km
2. a)$ 262
b) $ 691,56
c) R 6809,45
3 a )$744,25
b) R5500 X (1+0.12) = R6160
4 a) 1:1:1:1
b) Total Rent= R5300 + R492 = R5792, Each pays ¼ X R5792 = R1448
c) 492÷5792 X 100 = 8, 49%
d) (5650 – 5300)÷5300 X 100 = 6.6%
www.learnxtra.co.za
Follow us on Facebook: www.facebook.com/learnxtra
Contact us at: [email protected]
Page 3