140 pupils went for a singing competition and 68 of them achieved Gold certificates.
35 of the boys and
13 of the girls achieved Gold certificates. How many boys did not achieve Gold certificates?
| Girls |
Boys |
| 5 u |
3 p |
Achieved
Gold |
Did not achieve
Gold |
Achieved
Gold |
Did not achieve
Gold |
| 3 u |
2 u |
1 p |
2 p |
Number of pupils who did not achieve Gold certificates
= 140 - 68
= 72
3 u + 1 p = 68
1 p = 68 - 3 u --- (1)
2 u + 2 p = 72
2 p = 72 - 2 u --- (2)
Make p the same.
(1)
x22 p = 136 - 6 u --- (3)
(2) = (3)
72 - 2 u = 136 - 6 u
6 u - 2 u = 136 - 72
4 u = 64
1 u = 64 ÷ 4 = 16
Number of girls who achieved Gold certificates
= 3 u
= 3 x 16
= 48
Number of boys who achieved Gold certificates
= 68 - 48
= 20
Answer(s): 20
