Sixteen minutes ago, 80% of the pupils in a canteen were boys. 16 pupils left the canteen. As a result, the number of boys decreased by 20% and the number of girls decreased by 60%. How many pupils are in the canteen at first?
| |
Boys |
Girls |
Total |
| Before |
5 u |
1 u |
6 u |
| Change |
- 1 u |
- 0.6 u |
- 1.6 u |
| After |
4 u |
0.4 u |
4.4 u |
80% =
80100 =
45Number of boys who left the canteen
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of girls who left the canteen
= 60% x 1 u
=
60100 x 1 u
= 0.6 u
Total number of pupils who left the canteen
= 1 u + 0.6 u
= 1.6 u
1.6 u = 16
1 u = 16 ÷ 1.6 = 10
Number of pupils in the canteen at first
= 5 u + 1 u
= 6 u
= 6 x 10
= 60
Answer(s): 60
