In one History class of 82 students, 0.25 of the boys and
23 of the girls passed the exam. A total of 38 students passed the exam. How many boys failed the History exam?
| |
Boys |
Girls |
Total |
| Passed the test |
1 u |
2 p |
38 |
| Failed the test |
3 u |
1 p |
44 |
| Total |
4 u |
3 p |
82 |
0.25 of the boys =
14 of the boys
Total number of boys = 4 u
Total number of girls = 3 p
1 u + 2 p = 38 --- (1)
3 u + 1 p = 82 - 38
3 u + 1 p = 44 --- (2)
Make u the same.
(1)
x33 u + 6 p = 114 --- (3)
(3) - (2)
6 p - 1 p = 114 - 44
5 p = 70
1 p = 70 ÷ 5 = 14
From (2)
Number of boys who failed
= 44 - 1 p
= 44 - 14
= 30
Answer(s): 30
