The average of 61 numbers is 54. The average of first 31 numbers is 50.6 and that of last 31 numbers is 60.4. If the 31st number is excluded, then what is the average of the remaining numbers?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 52.45
Total sum = 61 × 54 = 3294
Sum of first 31 = 31 × 50.6 = 1568.6
Sum of last 31 = 31 × 60.4 = 1872.4
31st number = 1568.6 + 1872.4 − 3294 = 147
New sum = 3294 − 147 = 3147
Average of remaining 60 = 3147/60 = 52.45