Nine minutes ago, 70% of the children in a basketball court were girls. 81 children left the basketball court. As a result, the number of girls decreased by 30% and the number of boys decreased by 80%. How many children are in the basketball court at first?
| |
Girls |
Boys |
Total |
| Before |
10 u |
3 u |
13 u |
| Change |
- 3 u |
- 2.4 u |
- 5.4 u |
| After |
7 u |
0.6 u |
7.6 u |
70% =
70100 =
710Number of girls who left the basketball court
= 30% x 10 u
=
30100 x 10 u
= 3 u
Number of boys who left the basketball court
= 80% x 3 u
=
80100 x 3 u
= 2.4 u
Total number of children who left the basketball court
= 3 u + 2.4 u
= 5.4 u
5.4 u = 81
1 u = 81 ÷ 5.4 = 15
Number of children in the basketball court at first
= 10 u + 3 u
= 13 u
= 13 x 15
= 195
Answer(s): 195
