66 students from Class N and Class P took a Mathematics test. The average marks of the students was 90 marks. The average marks of the students in Class N was 96 marks and the average marks of the students in Class P was 85 marks. How many students were there in Class N?
Students in Class N |
Total scores in Class N |
Students in Class P |
Total scores in Class P |
Total scores of Class N and Class P |
66
|
66 x 96 = 6336 |
0
|
0
|
6336
|
65
|
65 x 96 = 6240 |
1
|
1 x 85 = 85 |
6325
|
30
|
30 x 96 = 2880 |
36
|
36 x 85 = 3060 |
5940
|
Total scores of Class P and Class N
= 66 x 90
= 5940
If all the students are in Class N,
total scores
= 66 x 96
= 6336
Big difference
= 6336 - 5940
= 396
Small difference
= 96 - 85
= 11
Number of students in Class P
= 396 ÷ 11
= 36
Number of students in Class N
= 66 - 36
= 30
Answer(s): 30