The number of students in classes A and B are 60 and 70, respectively. The average score in mathematics of students in class B is 57 and that of all students in classes A and B is 63. What is the average score of students in class A?
Answer & explanation
Correct answer: option 2
Let average score of students in class A = A
ATQ ,
60 × A + 70 × 57 = 130 × 63
60A + 3990 = 8190
60A = 4200
A = 70
So , average score of students in class A = 70