In one Social Studies class of 84 pupils, 0.25 of the boys and
78 of the girls passed the test. A total of 51 pupils passed the test. How many boys failed the Social Studies test?
|
Boys |
Girls |
Total |
Passed the test |
1 u |
7 p |
51 |
Failed the test |
3 u |
1 p |
33 |
Total |
4 u |
8 p |
84 |
0.25 of the boys =
14 of the boys
Total number of boys = 4 u
Total number of girls = 8 p
1 u + 7 p = 51 --- (1)
3 u + 1 p = 84 - 51
3 u + 1 p = 33 --- (2)
Make u the same.
(1)
x33 u + 21 p = 153 --- (3)
(3) - (2)
21 p - 1 p = 153 - 33
20 p = 120
1 p = 120 ÷ 20 = 6
From (2)
Number of boys who failed
= 33 - 1 p
= 33 - 6
= 27
Answer(s): 27