72 students from Class F and Class G took a Mathematics test. The average marks of the students was 86 marks. The average marks of the students in Class F was 89 marks and the average marks of the students in Class G was 80 marks. How many students were there in Class F?
Students in
Class F |
Total scores in
Class F |
Students in
Class G |
Total scores in
Class G |
Total scores of
Class F and Class G |
72
|
72 x 89 =
6408 |
0
|
0
|
6408
|
71
|
71 x 89 =
6319 |
1
|
1 x 80 =
80 |
6399
|
48
|
48 x 89 =
4272 |
24
|
24 x 80 =
1920 |
6192
|
Total scores of Class G and Class F
= 72 x 86
= 6192
If all the students are in Class F,
total scores
= 72 x 89
= 6408
Big difference
= 6408 - 6192
= 216
Small difference
= 89 - 80
= 9
Number of students in Class G
= 216 ÷ 9
= 24
Number of students in Class F
= 72 - 24
= 48
Answer(s): 48
