130 pupils went for a physical fitness test and 41 of them achieved Silver certificates.
25 of the girls and
15 of the boys achieved Silver certificates. How many girls did not achieve Silver certificates?
| Boys |
Girls |
| 5 u |
5 p |
Achieved
Silver |
Did not achieve
Silver |
Achieved
Silver |
Did not achieve
Silver |
| 2 u |
3 u |
1 p |
4 p |
Number of pupils who did not achieve Silver certificates
= 130 - 41
= 89
2 u + 1 p = 41
1 p = 41 - 2 u --- (1)
3 u + 4 p = 89
4 p = 89 - 3 u --- (2)
Make p the same.
(1)
x44 p = 164 - 8 u --- (3)
(2) = (3)
89 - 3 u = 164 - 8 u
8 u - 3 u = 164 - 89
5 u = 75
1 u = 75 ÷ 5 = 15
Number of boys who did not achieve Silver certificates
= 3 u
= 3 x 15
= 45
Number of girls who did not achieve Silver certificates
= 89 - 45
= 44
Answer(s): 44
