In one History class of 107 students, 0.25 of the girls and
45 of the boys passed the exam. A total of 35 students passed the exam. How many girls failed the History exam?
| |
Girls |
Boys |
Total |
| Passed the test |
1 u |
4 p |
35 |
| Failed the test |
3 u |
1 p |
72 |
| Total |
4 u |
5 p |
107 |
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 = 35 --- (1)
3 u + 1 p = 107 - 35
3 u + 1 p = 72 --- (2)
Make u the same.
(1)
x33 u + 12 p = 105 --- (3)
(3) - (2)
12 p - 1 p = 105 - 72
11 p = 33
1 p = 33 ÷ 11 = 3
From (2)
Number of girls who failed
= 72 - 1 p
= 72 - 3
= 69
Answer(s): 69
