UNIT 1
Had a look
Nearly there
Ratio
*
A
A
B
C
D
Nailed it!
Ratios are used to compare quantities.
You can find EQUIVALENT RATIOS by
multiplying or dividing by the same number.
Ratios are often used in real-life
situations such as cooking.
Jared is preparing the ingredients for a
pizza.
5:9
�2
He uses cheese, topping and dough in the
ratio 2 : 3 : 5.
He uses 70 grams of dough.
�2
10 : 18
�10
�10
1 : 1.8
This equivalent ratio is
in the form 1 : n.
This is useful for
calculations.
How many grams of topping will Jared use?
cheese : topping : dough
2 : 3
: 5
?
:
?
: 70 g
70
__
5  14
3  14  42 g of topping
t
A ratio can be written as a fraction.
In a drama group, if the ratio of boys to girls
2
is 2 : 5, then __
7 of the group are boys and
5
__
are
girls.
7
You can use ratios to work out
which of these jars of honey is
better VALUE FOR MONEY.
ra
f
580 : 319
STANDARD
450 : 270
�450
HONEY
450 g
£2.70
�450
HONEY
580 g
£3.19
�580
�580
1 : 0.55
The cost per gram is 0.55 p.
The SUPER jar is better value for money
because it costs less per gram.
D
1 : 0.6
The cost per gram is 0.6 p.
SUPER
grade
C
Three women won a total of £360.
They shared the money in the ratio 7 : 3 : 2.
Donna received the largest amount.
Work out the amount Donna received.
7  3  2  12
360
_____
 £30
12
£30  7  £210
Donna received £210.
Tom is making plum crumble.
For the crumble topping, he uses sugar, butter
and flour in the ratio 2 : 3 : 5.
Tom uses 250 g of plums for every 400 g of
crumble topping.
18
1. Work out the total number of parts.
2. Work out the value of 1 part.
3. Work out 7 parts (largest part) for
Donna.
You first need to convert 0.5 kg into grams.
Then work out how much crumble topping
Tom needs to make.
Tom has 0.5 kg of plums. He uses all of them.
Work out how much sugar, butter and flour he
will need for the crumble topping. (4 marks)
Questions on this topic are targeted at the grades indicated.
grade
C