170 pupils went for a singing competition and 49 of them achieved Gold certificates.
25 of the girls and
15 of the boys achieved Gold certificates. How many girls did not achieve Gold certificates?
| Boys |
Girls |
| 5 u |
5 p |
Achieved
Gold |
Did not achieve
Gold |
Achieved
Gold |
Did not achieve
Gold |
| 2 u |
3 u |
1 p |
4 p |
Number of pupils who did not achieve Gold certificates
= 170 - 49
= 121
2 u + 1 p = 49
1 p = 49 - 2 u --- (1)
3 u + 4 p = 121
4 p = 121 - 3 u --- (2)
Make p the same.
(1)
x44 p = 196 - 8 u --- (3)
(2) = (3)
121 - 3 u = 196 - 8 u
8 u - 3 u = 196 - 121
5 u = 75
1 u = 75 ÷ 5 = 15
Number of boys who did not achieve Gold certificates
= 3 u
= 3 x 15
= 45
Number of girls who did not achieve Gold certificates
= 121 - 45
= 76
Answer(s): 76
