In one Mathematics class of 99 pupils, 0.125 of the boys and
45 of the girls passed the exam. A total of 36 pupils passed the exam. How many boys failed the Mathematics exam?
| |
Boys |
Girls |
Total |
| Passed the test |
1 u |
4 p |
36 |
| Failed the test |
7 u |
1 p |
63 |
| Total |
8 u |
5 p |
99 |
0.125 of the boys =
18 of the boys
Total number of boys = 8 u
Total number of girls = 5 p
1 u + 4 p = 36 --- (1)
7 u + 1 p = 99 - 36
7 u + 1 p = 63 --- (2)
Make u the same.
(1)
x77 u + 28 p = 252 --- (3)
(3) - (2)
28 p - 1 p = 252 - 63
27 p = 189
1 p = 189 ÷ 27 = 7
From (2)
Number of boys who failed
= 63 - 1 p
= 63 - 7
= 56
Answer(s): 56
