50% of the pupils are girls. 40% of the girls and 80% of the boys wear spectacles. What percentage of the pupils do not wear spectacles?
| Girls |
Boys |
Total |
| 50% |
50% |
100% |
| Wear spectacles |
Do not wear |
Wear spectacles |
Do not wear |
|
| 20% |
30% |
40% |
10% |
100% |
Number of girls who wear spectacles
= 40% x 50%
=
40100 x 50%
= 20%
Number of boys who wear spectacles
= 80% x 50%
=
80100 x 50%
= 40%
Percentage of pupils who wear spectacles
= 20% + 40%
= 60%
Percentage of pupils who do not wear spectacles
= 100% - 60%
= 40%
Answer: 40%
