In a school, there is a total of 420 people.
25% are adults.
The rest are children.
The number of boys and girls is in the ratio of 1 : 4.
- What percentage of the people are boys?
- How many girls are there?
Adults |
Children |
Total |
1x5 |
3x5 |
4x5 |
|
Boys |
Girls |
|
|
1x3 |
4x3 |
|
5 u |
3 u |
12 u |
20 u |
(a)
25% =
25100 =
14 Adults : Children
1 : 4 - 1
1 : 3
Boys : Girls : Children
1 : 4 : 5
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 3 and 5.
LCM of 3 and 5 = 15
Percentage of the people that are boys
=
320 x 100%
= 15%
(b)
Total number of people = 20 u
20 u = 420
1 u = 420 ÷ 20 = 21
Number of girls
= 12 u
= 12 x 21
= 252
Answer(s): (a) 15%; (b) 252