In one History class of 120 pupils, 0.25 of the boys and
34 of the girls passed the mock exam. A total of 52 pupils passed the mock exam. How many boys failed the History mock exam?
| |
Boys |
Girls |
Total |
| Passed the test |
1 u |
3 p |
52 |
| Failed the test |
3 u |
1 p |
68 |
| Total |
4 u |
4 p |
120 |
0.25 of the boys =
14 of the boys
Total number of boys = 4 u
Total number of girls = 4 p
1 u + 3 p = 52 --- (1)
3 u + 1 p = 120 - 52
3 u + 1 p = 68 --- (2)
Make u the same.
(1)
x33 u + 9 p = 156 --- (3)
(3) - (2)
9 p - 1 p = 156 - 68
8 p = 88
1 p = 88 ÷ 8 = 11
From (2)
Number of boys who failed
= 68 - 1 p
= 68 - 11
= 57
Answer(s): 57
