If the average marks of three sections of Class IX, having 30, 45 and 50 students, respectively, is 80, 75 and 90, then the average marks of all the students of Class IX, is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 82.2.
Average = Total marks ÷ Total students
Total students = 30 + 45 + 50 = 125
Total marks = 30 × 80 + 45 × 75 + 50 × 90
= 2400 + 3375 + 4500 = 10275
Average = 10275 ÷ 125 = 82.2