The average number of girls in 2A, 2B and 2C is 11. This is 4 more than the average number of boys in the 3 rooms.
37 of the total number of boys are in 2C.
32 of the number of boys in 2B is the same as
37 of the total number of boys in the 3 rooms. What fraction of the total number of girls in the 3 rooms is in 2A if there are 18 pupils in 2A?
Boys in 2A |
Boys in 2B |
Boys in 2C |
Total boys |
4 |
3 |
7 |
|
2 |
|
7 |
2 u |
2 u |
3 u |
7 u |
32 of boys in 2B =
37 of all boys
Boys in 2B : All boys = 2 : 7
Average number of boys
= 11 - 4
= 7
Total number of boys
= 3 x 7
= 21
7 u = 21
1 u = 21 ÷ 7 = 3
Number of boys in Room 2A
= 2 u
= 2 x 3
= 6
Number of girls in Room 2A
= 18 - 6
= 12
Total number of girls
= 3 x 11
= 33
Girls in 2ATotal girls =
1233 =
411 Answer(s):
411