The average number of girls in 4A, 4B and 4C is 12. This is 4 more than the average number of boys in the 3 rooms.
112 of the total number of boys are in 4C.
12 of the number of boys in 4B is the same as
112 of the total number of boys in the 3 rooms. What fraction of the total number of girls in the 3 rooms is in 4A if there are 32 pupils in 4A?
| Boys in 4A |
Boys in 4B |
Boys in 4C |
Total boys |
| 11 |
1 |
12 |
| |
2 |
|
12 |
| 9 u |
2 u |
1 u |
12 u |
12 of boys in 4B =
112 of all boys
Boys in 4B : All boys = 2 : 12
Average number of boys
= 12 - 4
= 8
Total number of boys
= 3 x 8
= 24
12 u = 24
1 u = 24 ÷ 12 = 2
Number of boys in Room 4A
= 9 u
= 9 x 2
= 18
Number of girls in Room 4A
= 32 - 18
= 14
Total number of girls
= 3 x 12
= 36
Girls in 4ATotal girls =
1436 =
718 Answer(s):
718 
