Twelve minutes ago, 70% of the children in a hall were boys. 48 children left the hall. As a result, the number of boys decreased by 30% and the number of girls decreased by 60%. How many children are in the hall at first?
| |
Boys |
Girls |
Total |
| Before |
10 u |
3 u |
13 u |
| Change |
- 3 u |
- 1.8 u |
- 4.8 u |
| After |
7 u |
1.2 u |
8.2 u |
70% =
70100 =
710Number of boys who left the hall
= 30% x 10 u
=
30100 x 10 u
= 3 u
Number of girls who left the hall
= 60% x 3 u
=
60100 x 3 u
= 1.8 u
Total number of children who left the hall
= 3 u + 1.8 u
= 4.8 u
4.8 u = 48
1 u = 48 ÷ 4.8 = 10
Number of children in the hall at first
= 10 u + 3 u
= 13 u
= 13 x 10
= 130
Answer(s): 130
