In one Social Studies class of 112 pupils, 0.1 of the boys and
23 of the girls passed the mock exam. A total of 35 pupils passed the mock exam. How many boys failed the Social Studies mock exam?
| |
Boys |
Girls |
Total |
| Passed the test |
1 u |
2 p |
35 |
| Failed the test |
9 u |
1 p |
77 |
| Total |
10 u |
3 p |
112 |
0.1 of the boys =
110 of the boys
Total number of boys = 10 u
Total number of girls = 3 p
1 u + 2 p = 35 --- (1)
9 u + 1 p = 112 - 35
9 u + 1 p = 77 --- (2)
Make u the same.
(1)
x99 u + 18 p = 315 --- (3)
(3) - (2)
18 p - 1 p = 315 - 77
17 p = 238
1 p = 238 ÷ 17 = 14
From (2)
Number of boys who failed
= 77 - 1 p
= 77 - 14
= 63
Answer(s): 63
