60 pupils from Class D and Class E took a Mathematics test. The average marks of the pupils was 90 marks. The average marks of the pupils in Class D was 94 marks and the average marks of the pupils in Class E was 84 marks. How many pupils were there in Class D?
Pupils in
Class D |
Total scores in
Class D |
Pupils in
Class E |
Total scores in
Class E |
Total scores of
Class D and Class E |
60
|
60 x 94 =
5640 |
0
|
0
|
5640
|
59
|
59 x 94 =
5546 |
1
|
1 x 84 =
84 |
5630
|
36
|
36 x 94 =
3384 |
24
|
24 x 84 =
2016 |
5400
|
Total scores of Class E and Class D
= 60 x 90
= 5400
If all the pupils are in Class D,
total scores
= 60 x 94
= 5640
Big difference
= 5640 - 5400
= 240
Small difference
= 94 - 84
= 10
Number of pupils in Class E
= 240 ÷ 10
= 24
Number of pupils in Class D
= 60 - 24
= 36
Answer(s): 36
