In one Mathematics class of 85 pupils, 0.25 of the girls and
45 of the boys passed the exam. A total of 57 pupils passed the exam. How many girls failed the Mathematics exam?
| |
Girls |
Boys |
Total |
| Passed the test |
1 u |
4 p |
57 |
| Failed the test |
3 u |
1 p |
28 |
| Total |
4 u |
5 p |
85 |
0.25 of the girls =
14 of the girls
Total number of girls = 4 u
Total number of boys = 5 p
1 u + 4 p = 57 --- (1)
3 u + 1 p = 85 - 57
3 u + 1 p = 28 --- (2)
Make u the same.
(1)
x33 u + 12 p = 171 --- (3)
(3) - (2)
12 p - 1 p = 171 - 28
11 p = 143
1 p = 143 ÷ 11 = 13
From (2)
Number of girls who failed
= 28 - 1 p
= 28 - 13
= 15
Answer(s): 15
