77 pupils from Class T and Class U took a Mathematics test. The average marks of the pupils was 88 marks. The average marks of the pupils in Class T was 92 marks and the average marks of the pupils in Class U was 81 marks. How many pupils were there in Class T?
Pupils in
Class T |
Total scores in
Class T |
Pupils in
Class U |
Total scores in
Class U |
Total scores of
Class T and Class U |
77
|
77 x 92 =
7084 |
0
|
0
|
7084
|
76
|
76 x 92 =
6992 |
1
|
1 x 81 =
81 |
7073
|
49
|
49 x 92 =
4508 |
28
|
28 x 81 =
2268 |
6776
|
Total scores of Class U and Class T
= 77 x 88
= 6776
If all the pupils are in Class T,
total scores
= 77 x 92
= 7084
Big difference
= 7084 - 6776
= 308
Small difference
= 92 - 81
= 11
Number of pupils in Class U
= 308 ÷ 11
= 28
Number of pupils in Class T
= 77 - 28
= 49
Answer(s): 49
