The average number of boys in 4A, 4B and 4C is 11. This is 4 more than the average number of girls in the 3 rooms.
27 of the total number of girls are in 4C.
52 of the number of girls in 4B is the same as
57 of the total number of girls in the 3 rooms. What fraction of the total number of boys in the 3 rooms is in 4A if there are 21 children in 4A?
| Girls in 4A |
Girls in 4B |
Girls in 4C |
Total girls |
| 5 |
2 |
7 |
| |
2 |
|
7 |
| 3 u |
2 u |
2 u |
7 u |
52 of girls in 4B =
57 of all girls
Girls in 4B : All girls = 2 : 7
Average number of girls
= 11 - 4
= 7
Total number of girls
= 3 x 7
= 21
7 u = 21
1 u = 21 ÷ 7 = 3
Number of girls in Room 4A
= 3 u
= 3 x 3
= 9
Number of boys in Room 4A
= 21 - 9
= 12
Total number of boys
= 3 x 11
= 33
Boys in 4ATotal boys =
1233 =
411 Answer(s):
411 
