In a parade square,
310 of the boys wore spectacles. After 30 boys who wore spectacles entered the parade square, the percentage of boys who wore spectacles increased to 60%. How many boys in the parade square did not wear spectacles?
| |
Wore spectacles |
Did not wear spectacles |
| Before |
3x2 =
6 u |
7x2 =
14 u |
| Change |
+ 30 |
|
| After |
3x7 =
21 u |
2x7 =
14 u |
60% =
60100 =
35The number of boys who did not wear spectacles remains unchanged. LCM of 7 and 2 is 14.
Number of boys who wore spectacles and left
= 21 u - 6 u
= 15 u
15 u = 30
1 u = 30 ÷ 15 = 2
Number of boys who did not wear spectacles
= 14 u
= 14 x 2
= 28
Answer(s): 28
