In one Science class of 102 pupils, 0.1 of the boys and
34 of the girls passed the mock exam. A total of 57 pupils passed the mock exam. How many boys failed the Science mock exam?
| |
Boys |
Girls |
Total |
| Passed the test |
1 u |
3 p |
57 |
| Failed the test |
9 u |
1 p |
45 |
| Total |
10 u |
4 p |
102 |
0.1 of the boys =
110 of the boys
Total number of boys = 10 u
Total number of girls = 4 p
1 u + 3 p = 57 --- (1)
9 u + 1 p = 102 - 57
9 u + 1 p = 45 --- (2)
Make u the same.
(1)
x99 u + 27 p = 513 --- (3)
(3) - (2)
27 p - 1 p = 513 - 45
26 p = 468
1 p = 468 ÷ 26 = 18
From (2)
Number of boys who failed
= 45 - 1 p
= 45 - 18
= 27
Answer(s): 27
