CHANGING A DECIMAL TO A FRACTION
1) Type decimal into calculator
2) Press =
3) Press a b/c
Exercises
Change the following decimals to fractions
1) 0.54
4) 0.85
2) 0.36
5) 0.76
3) 0.95
6) 0.25
CHANGING A FRACTION TO A DECIMAL
1) Type fraction into calculator using the a b/c button
2) Press =
3) Press a b/c
Exercises
Change the following fractions to decimals
1) ¾
4) 9/10
2) 4/5
5) 89/100
3) 3/9
6) 45/250
CHANGING A PERCENT TO A FRACTION
1) Type the number of the percent into calculator e.g. if it was 45%, type in 45
2) Press a b/c then
100
3) Press =
Exercises
Change the following percents to a fraction
1) 44%
4) 68%
2) 35%
5) 22%
3) 98%
6) 75%
CHANGING A PERCENT TO A DECIMAL
1) Type the number of the percent into calculator e.g. if it was 76%, type 76
2) Press a b/c then
100
3) Press =
4) Press a b/c
Exercises
Change the following percentages to decimals
1) 36%
4) 98%
2) 56%
5) 34%
3) 76%
6) 23%
CHANGING A DECIMAL OR FRACTION TO A PERCENT
Percent means out of 100. For example, 75% means 75 out of 100.
To change a fraction or decimal to a %, simply multiply by 100
e.g.
0.62
2/5
=
0.62
=
62%
=
2/5
=
40%
x
100
X
100
Sometimes you are asked word questions in which you have to work out the percent.
For example: Ranui scored 7 out of 12 (7/12) in a test. What percentage is this?
If only 12 out of 30 students (12/30) have done their homework, what
percentage is this?
ANSWER:______________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Exercises
Change the following fractions and decimals to percents
1) 0.34
5) 1.98
2) 9/10
6) 3/5
3) 0.96
7) 0.85
4) 5/15
8) 19/20
Word questions
1) Layla got 14/20 in a recent English test. What percent is that?
2) Candice noticed that 13 out of the 34 people in her class were boys. What percent is
that?
3) Asher has saved $40 towards a new mountain bike which costs $260. What percentage
has he saved altogether?
TEACHER CHECK:________________________________________________________________
TEXT:
Units in Math
Page 45
Ex 5.1
FINDING A PERCENTAGE OF A QUANTITY
In math the word ‘of’ means times
e.g.
Find 15% of 40
40
x
15
shift
=
% button on calc
Answer:
e.g.
Goods are reduced in a sale by 15%. What will the savings be on goods that used
to be $30?
30
=
6
x
15%
$4.50
Exercises
Calculate
1) 30% of 600
5) 70% of 300
2) 25% of 960
6) 60% of 250
3) 20% of 1200
7) 90% of 640
4) 55% of 900
8) 40% of 1300
Word Questions
1) Shane is buying jeans at a local store. The cost $140 but there is a sale on with 20% off.
How much will Shane save?
_______________________________________________________________________
2) Lisa sees that if she buys 2 t-shirts at $20 she will get a 40% discount. What discount will
she get?
________________________________________________________________________
3) Tony needs to reduce his debt by 20% if he is going to be able to keep his house. If he is
debt is $4000, how much does he need to reduce his debt?
________________________________________________________________________
Teacher Check__________________________________________________________________
TEXT Units in Math
Page 46
Ex 5.2
INCREASING AND DECREASING BY A PERCENT
Your calculator again is your best friend here. Follow the example below to see how it is used:
Important:
Increase means
+
Decrease means
-
A shop owner adds on 40% to what they pay for goods. This is used to cover costs. If a shop
owner buys the goods for $45, what would they sell them for?
Type the following into the calculator:
45
x
Answer:
40
shift
=
+
$18
A student gets a 10% bonus on his pocket money if he does well at school. If he currently gets
$20 a week, how much will he get with his bonus?
20
x
Answer:
10
shift
=
+
$22
Lucy goes to a 20% off sale. She buys a pair of jeans that are $55. What price will she get them
for with the discount?
55
x
Answer:
20
$44
shift
=
-
Exercises
Calculate the following
1)
by 15%
2)
Increase 300
6)
140 by 40%
Increase 250
7)
by 20%
3)
8)
by 25%
9)
1500 by 45%
Decrease
375 by 45%
Increase
2000 by 65%
Decrease
450 by 10%
Increase
5)
Decrease
250 by 25%
Increase 200
4)
Decrease
10)
Decrease
4500 by 50%
Word Questions
1)
Laura is marking up the cost of t-shirts by 30%. If they originally
cost $40, what price is she marking the t-shirts up to?
________________________________________________________________________
________________________________________________________________________
2)
Jim sees a sign for 20% off all cars. If a car originally cost $4500,
what will the new price be with the 20% discount?
________________________________________________________________________
________________________________________________________________________
Teacher Check__________________________________________________________________
TEXT
Units in Maths
Page 47
Ex 5.3
Percentages
REVISION
DECIMALS
You need to know
Adding decimals
Subtracting decimals
Conversions
e.g. 6.4 + 4.3 + 8.2
e.g. 148.5 – 123.7
e.g. change 23kg into pounds
1) Three boys want to know what their combined height is. Bob is 1.7m tall, Kenny is 1.84m tall
and Paul is 1.67m tall. What is their combined height?
2) How much taller is Kenny than Bob?
3) If you buy a book at $6.35, a ruler at $1.25 and a pen at $2.95, how much would it cost?
4) Lara has $310.50 and Kendra has $230.90. How much more money does
Lara have than Kendra?
5) You are travelling to Australia for the next school holidays and have saved
up $340 NZ dollars. How much is this in Australian dollars if $1NZ =
0.79AUS?
6) Your sister is about to leave on her OE and has a stop over in Thailand. She wants to change
$250 NZ dollars into baht (Thailand money) to spend while she is there. The current exchange
rate is $1NZ = 17.49 baht. How much baht will she get?
7) For your next holiday you are looking to travel to Dubai. You want to have saved $1400 NZ
dollars to spend over there. If the current exchange rate is $1NZ = 1.79 dirhams, how much
dirhams will you get?
8) If 1kg = 2.2 pound, work out the following in pounds
a)
b)
c)
d)
3.5kg
9.8kg
55kg
95kg
PERCENTAGES
You need to know how to
Find a percent
e.g. Henry got 12 out of 20 in a test. What percent is that.
Find a
percentage of
Increase by a
percent
Decrease by a
percent
e.g. What is 20% of 50
e.g. Clothes at a store are marked up by 35%. If a t-shirt originally cost
$20, what will you pay for it?
e.g. Jeans at the Warehouse are advertised at 15% off. If they originally
cost $40, how much will you pay for them now?
1) Lewis got 14 out of 60 in his latest English test. What percent is that?
2) 18 out of the 28 people in Richard’s class were male.
a) What percent were male?
b) What percent were female?
3) In Dani’s class 30% were male. If his class had 40 students in it, how many would be male?
4) Gavin gets paid 30% of the value of goods he sells. How much will he get paid if he sells:
a) $4550
b) $350
c) $900
5) Laura works at the House of G and has been given the responsibility to mark-up the price of the
t-shirts by 30%. How much will the t-shirts cost if they were originally:
a) $20
b) $45
c) $9.50
6) Shane is shopping for some shorts. He goes into Hallensteins where they are advertising 30% off
all shorts. What would a pair of shorts cost Shane if they were originally:
a) $20
b) $55
c) $9.95
More Percentage Revision
Do this practice assessment by yourself and without looking at your notes. This will
show you whether you are ready to do the test for credits.
1) You get into a lift with 3 of your friends. The notice on the wall says the lift
will hold a maximum of 250kg. The weights of all 3 of you are as follows –
56kg, 49kg, 73kg and 65kg. Will the alarm sound in the lift to say it is overweight? SHOW WORKING
2) If Lisa was 73kg and Jodie was 56kg, how much heavier is Lisa?
3) Ben is travelling to Australia for a holiday and has saved $480 NZ dollars. How much AUS
dollars will he get if the exchange rate is $1NZ = 0.79 AUS?
4) Simon is trying to work out how much he weighs in pounds. He is told that 1kg = 2.2
pounds. If Simon weighs 89kg, how much does he weigh in pounds?
5) There are 352 pupils in Year 11 at Nayland.
a) 189 are male. What percentage of year 11 pupils is this?
b) 302 students live in zone. What percentage of year 11 pupils is this?
c) 22 do not have a cell phone. What percentage of year 11 pupils is this?
6) There are 80 classrooms in at Nayland College. 25% of them can hold more than 35
pupils. How many rooms can hold 35 pupils?
7) At the school canteen they are advertising that 10% of the cost of your food goes
towards charity. If you spend $15 on food, how much will get donated to charity?
8) There are 150 members on staff at Nayland. 20.5% of them are under the age of 30.
How many are under the age of 30?
9) In 2000, the Nayland roll was 1200. By 2009 it had increased by 25%. How many
students are on the roll for 2009?
10) The student office at Nayland are offering 20% off calculators. If the
calculator costs $20, how much will you now pay for it?
11) At the school canteen, milkshakes are normally 500mL. This week they are
offering a special where you get 35% extra. How much will you now get?