175 pupils went for a dancing competition and 54 of them achieved Silver certificates.
25 of the boys and
15 of the girls achieved Silver certificates. How many boys did not achieve Silver certificates?
| Girls |
Boys |
| 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
= 175 - 54
= 121
2 u + 1 p = 54
1 p = 54 - 2 u --- (1)
3 u + 4 p = 121
4 p = 121 - 3 u --- (2)
Make p the same.
(1)
x44 p = 216 - 8 u --- (3)
(2) = (3)
121 - 3 u = 216 - 8 u
8 u - 3 u = 216 - 121
5 u = 95
1 u = 95 ÷ 5 = 19
Number of girls who achieved Silver certificates
= 2 u
= 2 x 19
= 38
Number of boys who achieved Silver certificates
= 54 - 38
= 16
Answer(s): 16
