Fourteen minutes ago, 80% of the pupils in a hall were boys. 18 more pupils entered the hall. As a result, the number of boys increased by 20% and the number of girls increased by 80%. How many pupils are in the hall now?
| |
Boys |
Girls |
Total |
| Before |
5 u |
1 u |
6 u |
| Change |
+ 1 u |
+ 0.8 u |
+ 1.8 u |
| After |
6 u |
1.8 u |
7.8 u |
80% =
80100 =
45Number of more boys who entered the hall
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of more girls who entered the hall
= 80% x 1 u
=
80100 x 1 u
= 0.8 u
Total number of more pupils who entered the hall
= 1 u + 0.8 u
= 1.8 u
1.8 u = 18
1 u = 18 ÷ 1.8 = 10
Number of pupils in the hall now
= 6 u + 1.8 u
= 7.8 u
= 7.8 x 10
= 78
Answer(s): 78
