72 students from Class Q and Class R took a Mathematics test. The average marks of the students was 87 marks. The average marks of the students in Class Q was 92 marks and the average marks of the students in Class R was 83 marks. How many students were there in Class Q?
Students in
Class Q |
Total scores in
Class Q |
Students in
Class R |
Total scores in
Class R |
Total scores of
Class Q and Class R |
72
|
72 x 92 =
6624 |
0
|
0
|
6624
|
71
|
71 x 92 =
6532 |
1
|
1 x 83 =
83 |
6615
|
32
|
32 x 92 =
2944 |
40
|
40 x 83 =
3320 |
6264
|
Total scores of Class R and Class Q
= 72 x 87
= 6264
If all the students are in Class Q,
total scores
= 72 x 92
= 6624
Big difference
= 6624 - 6264
= 360
Small difference
= 92 - 83
= 9
Number of students in Class R
= 360 ÷ 9
= 40
Number of students in Class Q
= 72 - 40
= 32
Answer(s): 32
