Nineteen minutes ago, 80% of the students in a canteen were girls. 27 students left the canteen. As a result, the number of girls decreased by 40% and the number of boys decreased by 70%. How many students are in the canteen at first?
|
Girls |
Boys |
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 girls who left the canteen
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of boys who left the canteen
= 70% x 1 u
=
70100 x 1 u
= 0.7 u
Total number of students who left the canteen
= 2 u + 0.7 u
= 2.7 u
2.7 u = 27
1 u = 27 ÷ 2.7 = 10
Number of students in the canteen at first
= 5 u + 1 u
= 6 u
= 6 x 10
= 60
Answer(s): 60