175 students went for a physical fitness test and 50 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 students who did not achieve Silver certificates
= 175 - 50
= 125
2 u + 1 p = 50
1 p = 50 - 2 u --- (1)
3 u + 4 p = 125
4 p = 125 - 3 u --- (2)
Make p the same.
(1)
x44 p = 200 - 8 u --- (3)
(2) = (3)
125 - 3 u = 200 - 8 u
8 u - 3 u = 200 - 125
5 u = 75
1 u = 75 ÷ 5 = 15
Number of girls who achieved Silver certificates
= 2 u
= 2 x 15
= 30
Number of boys who achieved Silver certificates
= 50 - 30
= 20
Answer(s): 20