52 students from Class B and Class C took a Mathematics test. The average marks of the students was 75 marks. The average marks of the students in Class B was 83 marks and the average marks of the students in Class C was 70 marks. How many students were there in Class B?
Students in
Class B |
Total scores in
Class B |
Students in
Class C |
Total scores in
Class C |
Total scores of
Class B and Class C |
52
|
52 x 83 =
4316 |
0
|
0
|
4316
|
51
|
51 x 83 =
4233 |
1
|
1 x 70 =
70 |
4303
|
20
|
20 x 83 =
1660 |
32
|
32 x 70 =
2240 |
3900
|
Total scores of Class C and Class B
= 52 x 75
= 3900
If all the students are in Class B,
total scores
= 52 x 83
= 4316
Big difference
= 4316 - 3900
= 416
Small difference
= 83 - 70
= 13
Number of students in Class C
= 416 ÷ 13
= 32
Number of students in Class B
= 52 - 32
= 20
Answer(s): 20
