72 students from Class W and Class X took a Mathematics test. The average marks of the students was 83 marks. The average marks of the students in Class W was 88 marks and the average marks of the students in Class X was 76 marks. How many students were there in Class W?
Students in
Class W |
Total scores in
Class W |
Students in
Class X |
Total scores in
Class X |
Total scores of
Class W and Class X |
72
|
72 x 88 =
6336 |
0
|
0
|
6336
|
71
|
71 x 88 =
6248 |
1
|
1 x 76 =
76 |
6324
|
42
|
42 x 88 =
3696 |
30
|
30 x 76 =
2280 |
5976
|
Total scores of Class X and Class W
= 72 x 83
= 5976
If all the students are in Class W,
total scores
= 72 x 88
= 6336
Big difference
= 6336 - 5976
= 360
Small difference
= 88 - 76
= 12
Number of students in Class X
= 360 ÷ 12
= 30
Number of students in Class W
= 72 - 30
= 42
Answer(s): 42
