The average of 23 numbers is 51. The average of the first 12 numbers is 49 and the average of the last 12 numbers is 54. If the twelfth number is removed, then the average of the remaining numbers ( correct to two decimal places ) is :
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 50.45
The sum of 23 numbers = 23 × 51 = 1173.
The sum of the first 12 numbers = 12 × 49 = 588.
The sum of the last 12 numbers = 12 × 54 = 648
Twelfth number = 588 + 648 - 1173 = 63.
The sum of the number except the twelfth number = 1173 - 63 = 1110.
Average of these 22 numbers = 1110/22 = 50.45.