54 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 90 marks and the average marks of the students in Class G was 84 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 |
54
|
54 x 90 =
4860 |
0
|
0
|
4860
|
53
|
53 x 90 =
4770 |
1
|
1 x 84 =
84 |
4854
|
18
|
18 x 90 =
1620 |
36
|
36 x 84 =
3024 |
4644
|
Total scores of Class G and Class F
= 54 x 86
= 4644
If all the students are in Class F,
total scores
= 54 x 90
= 4860
Big difference
= 4860 - 4644
= 216
Small difference
= 90 - 84
= 6
Number of students in Class G
= 216 ÷ 6
= 36
Number of students in Class F
= 54 - 36
= 18
Answer(s): 18
