In a parade square,
35 of the pupils wore spectacles. After 150 pupils who wore spectacles left the parade square, the percentage of pupils who wore spectacles decreased to 30%. How many pupils in the parade square did not wear spectacles?
| |
Wore spectacles |
Did not wear spectacles |
| Before |
3x7 =
21 u |
2x7 =
14 u |
| Change |
- 150 |
|
| After |
3x2 =
6 u |
7x2 =
14 u |
30% =
30100 =
310The number of pupils who did not wear spectacles remains unchanged. LCM of 2 and 7 is 14.
Number of pupils who wore spectacles and left
= 21 u - 6 u
= 15 u
15 u = 150
1 u = 150 ÷ 15 = 10
Number of pupils who did not wear spectacles
= 14 u
= 14 x 10
= 140
Answer(s): 140
