The average number of girls in 6A, 6B and 6C is 11. This is 3 more than the average number of boys in the 3 rooms.
38 of the total number of boys are in 6C.
52 of the number of boys in 6B is the same as
58 of the total number of boys in the 3 rooms. What fraction of the total number of girls in the 3 rooms is in 6A if there are 20 pupils in 6A?
| Boys in 6A |
Boys in 6B |
Boys in 6C |
Total boys |
| 5 |
3 |
8 |
| |
2 |
|
8 |
| 3 u |
2 u |
3 u |
8 u |
52 of boys in 6B =
58 of all boys
Boys in 6B : All boys = 2 : 8
Average number of boys
= 11 - 3
= 8
Total number of boys
= 3 x 8
= 24
8 u = 24
1 u = 24 ÷ 8 = 3
Number of boys in Room 6A
= 3 u
= 3 x 3
= 9
Number of girls in Room 6A
= 20 - 9
= 11
Total number of girls
= 3 x 11
= 33
Girls in 6ATotal girls =
1133 =
13 Answer(s):
13 
