In a school field,
14 of the pupils wore glasses. After 72 pupils who wore glasses entered the school field, the percentage of pupils who wore glasses increased to 75%. How many pupils in the school field did not wear glasses?
| |
Wore glasses |
Did not wear glasses |
| Before |
1x1 =
1 u |
3x1 =
3 u |
| Change |
+ 72 |
|
| After |
3x3 =
9 u |
1x3 =
3 u |
75% =
75100 =
34The number of pupils who did not wear glasses remains unchanged. LCM of 3 and 1 is 3.
Number of pupils who wore glasses and left
= 9 u - 1 u
= 8 u
8 u = 72
1 u = 72 ÷ 8 = 9
Number of pupils who did not wear glasses
= 3 u
= 3 x 9
= 27
Answer(s): 27
