105 students went for a dancing competition and 55 of them achieved Bronze certificates.
35 of the girls and
13 of the boys achieved Bronze certificates. How many girls did not achieve Bronze certificates?
| Boys |
Girls |
| 5 u |
3 p |
Achieved
Bronze |
Did not achieve
Bronze |
Achieved
Bronze |
Did not achieve
Bronze |
| 3 u |
2 u |
1 p |
2 p |
Number of students who did not achieve Bronze certificates
= 105 - 55
= 50
3 u + 1 p = 55
1 p = 55 - 3 u --- (1)
2 u + 2 p = 50
2 p = 50 - 2 u --- (2)
Make p the same.
(1)
x22 p = 110 - 6 u --- (3)
(2) = (3)
50 - 2 u = 110 - 6 u
6 u - 2 u = 110 - 50
4 u = 60
1 u = 60 ÷ 4 = 15
Number of boys who did not achieve Bronze certificates
= 2 u
= 2 x 15
= 30
Number of girls who did not achieve Bronze certificates
= 50 - 30
= 20
Answer(s): 20
