66 pupils from Class D and Class E took a Mathematics test. The average marks of the pupils was 80 marks. The average marks of the pupils in Class D was 84 marks and the average marks of the pupils in Class E was 72 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 |
66
|
66 x 84 =
5544 |
0
|
0
|
5544
|
65
|
65 x 84 =
5460 |
1
|
1 x 72 =
72 |
5532
|
44
|
44 x 84 =
3696 |
22
|
22 x 72 =
1584 |
5280
|
Total scores of Class E and Class D
= 66 x 80
= 5280
If all the pupils are in Class D,
total scores
= 66 x 84
= 5544
Big difference
= 5544 - 5280
= 264
Small difference
= 84 - 72
= 12
Number of pupils in Class E
= 264 ÷ 12
= 22
Number of pupils in Class D
= 66 - 22
= 44
Answer(s): 44
