In a school, there is a total of 660 people.
40% are adults.
The rest are children.
The number of girls and boys is in the ratio of 5 : 7.
- What percentage of the people are girls?
- How many boys are there?
Adults |
Children |
Total |
2x4 |
3x4 |
5x4 |
|
Girls |
Boys |
|
|
5x1 |
7x1 |
|
8 u |
5 u |
7 u |
20 u |
(a)
40% =
40100 =
25 Adults : Children
2 : 5 - 2
2 : 3
Girls : Boys : Children
5 : 7 : 12
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 3 and 12.
LCM of 3 and 12 = 12
Percentage of the people that are girls
=
520 x 100%
= 25%
(b)
Total number of people = 20 u
20 u = 660
1 u = 660 ÷ 20 = 33
Number of boys
= 7 u
= 7 x 33
= 231
Answer(s): (a) 25%; (b) 231