In one Science class of 84 pupils, 0.25 of the girls and
34 of the boys passed the exam. A total of 49 pupils passed the exam. How many girls failed the Science exam?
| |
Girls |
Boys |
Total |
| Passed the test |
1 u |
3 p |
49 |
| Failed the test |
3 u |
1 p |
35 |
| Total |
4 u |
4 p |
84 |
0.25 of the girls =
14 of the girls
Total number of girls = 4 u
Total number of boys = 4 p
1 u + 3 p = 49 --- (1)
3 u + 1 p = 84 - 49
3 u + 1 p = 35 --- (2)
Make u the same.
(1)
x33 u + 9 p = 147 --- (3)
(3) - (2)
9 p - 1 p = 147 - 35
8 p = 112
1 p = 112 ÷ 8 = 14
From (2)
Number of girls who failed
= 35 - 1 p
= 35 - 14
= 21
Answer(s): 21
