The average of 41 numbers is 63. The average of first 21 number is 61.5 and that of last 21 numbers is 65.5. if 21st number is excluded then the average of remaining numbers is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 62.475.
Given -
Average of 41 numbers = 63
Average of first 21 numbers = 61.5
Average of last 21 numbers = 65.5
Average = sum of observations/number of observations
Sum of 41 numbers = 41 × 63 = 2583
Sum of first 21 numbers = 61.5 × 21 = 129.5
Sum of last 21 numbers = 65.5 × 21 = 1375.5
21st number = 1375.5 - 1291.5 = 84
Average of numbers excluding 21st number = (2583 - 84)/40 = 62.475