Fourteen minutes ago, 80% of the students in a school field were boys. 54 students left the school field. As a result, the number of boys decreased by 40% and the number of girls decreased by 70%. How many students are in the school field at first?
|
Boys |
Girls |
Total |
Before |
5 u |
1 u |
6 u |
Change |
- 2 u |
- 0.7 u |
- 2.7 u |
After |
3 u |
0.3 u |
3.3 u |
80% =
80100 =
45Number of boys who left the school field
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of girls who left the school field
= 70% x 1 u
=
70100 x 1 u
= 0.7 u
Total number of students who left the school field
= 2 u + 0.7 u
= 2.7 u
2.7 u = 54
1 u = 54 ÷ 2.7 = 20
Number of students in the school field at first
= 5 u + 1 u
= 6 u
= 6 x 20
= 120
Answer(s): 120