In a school, there is a total of 780 people.
10% are adults.
The rest are children.
The number of boys and girls is in the ratio of 1 : 5.
- What percentage of the people are boys?
- How many girls are there?
Adults |
Children |
Total |
1x2 |
9x2 |
10x2 |
|
Boys |
Girls |
|
|
1x3 |
5x3 |
|
2 u |
3 u |
15 u |
20 u |
(a)
10% =
10100 =
110 Adults : Children
1 : 10 - 1
1 : 9
Boys : Girls : Children
1 : 5 : 6
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 9 and 6.
LCM of 9 and 6 = 18
Percentage of the people that are boys
=
320 x 100%
= 15%
(b)
Total number of people = 20 u
20 u = 780
1 u = 780 ÷ 20 = 39
Number of girls
= 15 u
= 15 x 39
= 585
Answer(s): (a) 15%; (b) 585