In one Mathematics class of 84 pupils, 0.25 of the boys and
34 of the girls passed the exam. A total of 53 pupils passed the exam. How many boys failed the Mathematics exam?
|
Boys |
Girls |
Total |
Passed the test |
1 u |
3 p |
53 |
Failed the test |
3 u |
1 p |
31 |
Total |
4 u |
4 p |
84 |
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 = 53 --- (1)
3 u + 1 p = 84 - 53
3 u + 1 p = 31 --- (2)
Make u the same.
(1)
x33 u + 9 p = 159 --- (3)
(3) - (2)
9 p - 1 p = 159 - 31
8 p = 128
1 p = 128 ÷ 8 = 16
From (2)
Number of boys who failed
= 31 - 1 p
= 31 - 16
= 15
Answer(s): 15