The average number of boys in 1A, 1B and 1C is 10. This is 2 more than the average number of girls in the 3 rooms.
18 of the total number of girls are in 1C.
52 of the number of girls in 1B is the same as
58 of the total number of girls in the 3 rooms. What fraction of the total number of boys in the 3 rooms is in 1A if there are 25 children in 1A?
| Girls in 1A |
Girls in 1B |
Girls in 1C |
Total girls |
| 7 |
1 |
8 |
| |
2 |
|
8 |
| 5 u |
2 u |
1 u |
8 u |
52 of girls in 1B =
58 of all girls
Girls in 1B : All girls = 2 : 8
Average number of girls
= 10 - 2
= 8
Total number of girls
= 3 x 8
= 24
8 u = 24
1 u = 24 ÷ 8 = 3
Number of girls in Room 1A
= 5 u
= 5 x 3
= 15
Number of boys in Room 1A
= 25 - 15
= 10
Total number of boys
= 3 x 10
= 30
Boys in 1ATotal boys =
1030 =
13 Answer(s):
13 
