93 pupils went for a spelling test and 47 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
= 93 - 47
= 46
3 u + 1 p = 47
1 p = 47 - 3 u --- (1)
2 u + 2 p = 46
2 p = 46 - 2 u --- (2)
Make p the same.
(1)
x22 p = 94 - 6 u --- (3)
(2) = (3)
46 - 2 u = 94 - 6 u
6 u - 2 u = 94 - 46
4 u = 48
1 u = 48 ÷ 4 = 12
Number of girls who achieved Gold certificates
= 3 u
= 3 x 12
= 36
Number of boys who achieved Gold certificates
= 47 - 36
= 11
Answer(s): 11