In a school, there is a total of 2800 people.
10% 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 |
1x10 |
9x10 |
10x10 |
|
Girls |
Boys |
|
|
3x9 |
7x9 |
|
10 u |
27 u |
63 u |
100 u |
(a)
10% =
10100 =
110 Adults : Children
1 : 10 - 1
1 : 9
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 9 and 10.
LCM of 9 and 10 = 90
Percentage of the people that are girls
=
27100 x 100%
= 27%
(b)
Total number of people = 100 u
100 u = 2800
1 u = 2800 ÷ 100 = 28
Number of boys
= 63 u
= 63 x 28
= 1764
Answer(s): (a) 27%; (b) 1764