Page 295 - Math Smart - 7

O There are 21 girls and 15 boys in the Stage 7 class.
a) What is the ratio of the number of girls to the number of boys?
b) What is the ratio of the number of boys to the number of girls?
Give both answers in their simplest form.

©* Challenge! Simplify each of these ratios,
C) 2 . 7 _5_
X
a) b) i d) I
10 12

o Journal Writing <^^eese Scones

The ingredients needed to make cheese scones are listed.
^'^Ogpour
a) Write down the ratio of the amount of flour needed to the amount
of butter needed. Simplify your answer.
b) Write down the ratio of the amount of cheese needed to the amount
of butter needed. Simplify your answer.
c) Abdul says that the ratio of the amount of cheese needed to the
amount of milk needed is 1 : 5. Is he correct? Explain your answer.
d) As Liana has only 20 g of cheese, she decides to adjust the amount of
the ingredients used to make a smaller batch of scones.
i) How many grams of butter does she need?
ii) How many grams of flour does she need?

13.1.1 Sharing quantities in a given ratio

Work backwards.
Example 5
Check that 250: 100
Yi Ling and Grace share a sum of money in the ratio 5 : 2. simplifies to 5 : 2 as given
Yi Ling receives $250. in the problem.
a) How much does Grace receive? 250:100
c .)
b) Find the sum of money that the two girls are sharing.

Solution ^ 5:2 ^ /
$250
Yi Ling
Alternative solution
Grace using fractions
Yi Ling receives | of the
a) 5 parts—►$250 b) 7 parts—^7 X $50 = $350 sum of money.
1 part—►$250v5 = $50 or Grace receives y of the
money.
2 parts —► 2 x $50 = $100 Sum of money = $250 + $100 = $350
Amount of money Grace
Grace receives $100. The sum of money that the two girls receives
are sharing is $350. = $250 V f X f
= $250 X ^ X 2

= $250 X I
= $100