65 pupils from Class X and Class Y took a Mathematics test. The average marks of the pupils was 88 marks. The average marks of the pupils in Class X was 94 marks and the average marks of the pupils in Class Y was 84 marks. How many pupils were there in Class X?
Pupils in
Class X |
Total scores in
Class X |
Pupils in
Class Y |
Total scores in
Class Y |
Total scores of
Class X and Class Y |
65
|
65 x 94 =
6110 |
0
|
0
|
6110
|
64
|
64 x 94 =
6016 |
1
|
1 x 84 =
84 |
6100
|
26
|
26 x 94 =
2444 |
39
|
39 x 84 =
3276 |
5720
|
Total scores of Class Y and Class X
= 65 x 88
= 5720
If all the pupils are in Class X,
total scores
= 65 x 94
= 6110
Big difference
= 6110 - 5720
= 390
Small difference
= 94 - 84
= 10
Number of pupils in Class Y
= 390 ÷ 10
= 39
Number of pupils in Class X
= 65 - 39
= 26
Answer(s): 26
