52 pupils from Class M and Class N took a Mathematics test. The average marks of the pupils was 77 marks. The average marks of the pupils in Class M was 86 marks and the average marks of the pupils in Class N was 73 marks. How many pupils were there in Class M?
Pupils in
Class M |
Total scores in
Class M |
Pupils in
Class N |
Total scores in
Class N |
Total scores of
Class M and Class N |
52
|
52 x 86 =
4472 |
0
|
0
|
4472
|
51
|
51 x 86 =
4386 |
1
|
1 x 73 =
73 |
4459
|
16
|
16 x 86 =
1376 |
36
|
36 x 73 =
2628 |
4004
|
Total scores of Class N and Class M
= 52 x 77
= 4004
If all the pupils are in Class M,
total scores
= 52 x 86
= 4472
Big difference
= 4472 - 4004
= 468
Small difference
= 86 - 73
= 13
Number of pupils in Class N
= 468 ÷ 13
= 36
Number of pupils in Class M
= 52 - 36
= 16
Answer(s): 16
