The average number of boys in 1A, 1B and 1C is 16. This is 4 more than the average number of girls in the 3 rooms.
112 of the total number of girls are in 1C.
12 of the number of girls in 1B is the same as
112 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 39 pupils in 1A?
| Girls in 1A |
Girls in 1B |
Girls in 1C |
Total girls |
| 11 |
1 |
12 |
| |
2 |
|
12 |
| 9 u |
2 u |
1 u |
12 u |
12 of girls in 1B =
112 of all girls
Girls in 1B : All girls = 2 : 12
Average number of girls
= 16 - 4
= 12
Total number of girls
= 3 x 12
= 36
12 u = 36
1 u = 36 ÷ 12 = 3
Number of girls in Room 1A
= 9 u
= 9 x 3
= 27
Number of boys in Room 1A
= 39 - 27
= 12
Total number of boys
= 3 x 16
= 48
Boys in 1ATotal boys =
1248 =
14 Answer(s):
14 
