In a parade square,
25 of the pupils wore glasses. After 45 pupils who wore glasses left the parade square, the percentage of pupils who wore glasses decreased to 20%. How many pupils in the parade square did not wear glasses?
| |
Wore glasses |
Did not wear glasses |
| Before |
2x4 =
8 u |
3x4 =
12 u |
| Change |
- 45 |
|
| After |
1x3 =
3 u |
4x3 =
12 u |
20% =
20100 =
15The number of pupils who did not wear glasses remains unchanged. LCM of 3 and 4 is 12.
Number of pupils who wore glasses and left
= 8 u - 3 u
= 5 u
5 u = 45
1 u = 45 ÷ 5 = 9
Number of pupils who did not wear glasses
= 12 u
= 12 x 9
= 108
Answer(s): 108
