A class of 30 students appeared in a test. The average score of 12 students is 60, and that of the rest is 80. What is the average score of the class?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 72.
Short method:
12 → 60
18 → 80
Average score of the class = 60 + = 60 + 12 = 72
Alternate method:
The total score of 12 students = 12 × 60 = 720
Remaining students = 30 - 12 = 18
Total score of 18 students = 18 × 80 = 1440
Average = (720 + 1440)/30 = 2160/30 = 72