In a parade square,
13 of the boys wore spectacles. After 20 boys who wore spectacles entered the parade square, the percentage of boys who wore spectacles increased to 75%. How many boys in the parade square did not wear spectacles?
| |
Wore spectacles |
Did not wear spectacles |
| Before |
1x1 =
1 u |
2x1 =
2 u |
| Change |
+ 20 |
|
| After |
3x2 =
6 u |
1x2 =
2 u |
75% =
75100 =
34The number of boys who did not wear spectacles remains unchanged. LCM of 2 and 1 is 2.
Number of boys who wore spectacles and left
= 6 u - 1 u
= 5 u
5 u = 20
1 u = 20 ÷ 5 = 4
Number of boys who did not wear spectacles
= 2 u
= 2 x 4
= 8
Answer(s): 8
