147 pupils went for a physical fitness test and 48 of them achieved Gold certificates.
25 of the girls and
14 of the boys achieved Gold certificates. How many girls did not achieve Gold certificates?
| Boys |
Girls |
| 5 u |
4 p |
Achieved
Gold |
Did not achieve
Gold |
Achieved
Gold |
Did not achieve
Gold |
| 2 u |
3 u |
1 p |
3 p |
Number of pupils who did not achieve Gold certificates
= 147 - 48
= 99
2 u + 1 p = 48
1 p = 48 - 2 u --- (1)
3 u + 3 p = 99
3 p = 99 - 3 u --- (2)
Make p the same.
(1)
x33 p = 144 - 6 u --- (3)
(2) = (3)
99 - 3 u = 144 - 6 u
6 u - 3 u = 144 - 99
3 u = 45
1 u = 45 ÷ 3 = 15
Number of boys who achieved Gold certificates
= 2 u
= 2 x 15
= 30
Number of girls who achieved Gold certificates
= 48 - 30
= 18
Answer(s): 18
