Nineteen minutes ago, 60% of the children in a school field were girls. 34 children left the school field. As a result, the number of girls decreased by 40% and the number of boys decreased by 70%. How many children are in the school field at first?
| |
Girls |
Boys |
Total |
| Before |
5 u |
2 u |
7 u |
| Change |
- 2 u |
- 1.4 u |
- 3.4 u |
| After |
3 u |
0.6 u |
3.6 u |
60% =
60100 =
35Number of girls who left the school field
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of boys who left the school field
= 70% x 2 u
=
70100 x 2 u
= 1.4 u
Total number of children who left the school field
= 2 u + 1.4 u
= 3.4 u
3.4 u = 34
1 u = 34 ÷ 3.4 = 10
Number of children in the school field at first
= 5 u + 2 u
= 7 u
= 7 x 10
= 70
Answer(s): 70
