Eighteen minutes ago, 70% of the pupils in a parade square were girls. 94 pupils left the parade square. As a result, the number of girls decreased by 20% and the number of boys decreased by 90%. How many pupils are in the parade square at first?
| |
Girls |
Boys |
Total |
| Before |
10 u |
3 u |
13 u |
| Change |
- 2 u |
- 2.7 u |
- 4.7 u |
| After |
8 u |
0.3 u |
8.3 u |
70% =
70100 =
710Number of girls who left the parade square
= 20% x 10 u
=
20100 x 10 u
= 2 u
Number of boys who left the parade square
= 90% x 3 u
=
90100 x 3 u
= 2.7 u
Total number of pupils who left the parade square
= 2 u + 2.7 u
= 4.7 u
4.7 u = 94
1 u = 94 ÷ 4.7 = 20
Number of pupils in the parade square at first
= 10 u + 3 u
= 13 u
= 13 x 20
= 260
Answer(s): 260
