In a school, there is a total of 5000 people.
30% are adults.
The rest are children.
The number of girls and boys is in the ratio of 3 : 7.
- What percentage of the people are girls?
- How many boys are there?
Adults |
Children |
Total |
3x10 |
7x10 |
10x10 |
|
Girls |
Boys |
|
|
3x7 |
7x7 |
|
30 u |
21 u |
49 u |
100 u |
(a)
30% =
30100 =
310 Adults : Children
3 : 10 - 3
3 : 7
Girls : Boys : Children
3 : 7 : 10
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 7 and 10.
LCM of 7 and 10 = 70
Percentage of the people that are girls
=
21100 x 100%
= 21%
(b)
Total number of people = 100 u
100 u = 5000
1 u = 5000 ÷ 100 = 50
Number of boys
= 49 u
= 49 x 50
= 2450
Answer(s): (a) 21%; (b) 2450