The average number of girls in 1A, 1B and 1C is 13. This is 2 more than the average number of boys in the 3 rooms.
311 of the total number of boys are in 1C.
32 of the number of boys in 1B is the same as
311 of the total number of boys in the 3 rooms. What fraction of the total number of girls in the 3 rooms is in 1A if there are 30 students in 1A?
| Boys in 1A |
Boys in 1B |
Boys in 1C |
Total boys |
| 8 |
3 |
11 |
| |
2 |
|
11 |
| 6 u |
2 u |
3 u |
11 u |
32 of boys in 1B =
311 of all boys
Boys in 1B : All boys = 2 : 11
Average number of boys
= 13 - 2
= 11
Total number of boys
= 3 x 11
= 33
11 u = 33
1 u = 33 ÷ 11 = 3
Number of boys in Room 1A
= 6 u
= 6 x 3
= 18
Number of girls in Room 1A
= 30 - 18
= 12
Total number of girls
= 3 x 13
= 39
Girls in 1ATotal girls =
1239 =
413 Answer(s):
413 
