In a school, there is a total of 1000 people.
30% are adults.
The rest are children.
The number of girls and boys is in the ratio of 1 : 9.
- What percentage of the people are girls?
- How many boys are there?
Adults |
Children |
Total |
3x10 |
7x10 |
10x10 |
|
Girls |
Boys |
|
|
1x7 |
9x7 |
|
30 u |
7 u |
63 u |
100 u |
(a)
30% =
30100 =
310 Adults : Children
3 : 10 - 3
3 : 7
Girls : Boys : Children
1 : 9 : 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
=
7100 x 100%
= 7%
(b)
Total number of people = 100 u
100 u = 1000
1 u = 1000 ÷ 100 = 10
Number of boys
= 63 u
= 63 x 10
= 630
Answer(s): (a) 7%; (b) 630