Question

The average of 13 numbers is 42. The average of the first 7 numbers is 38 and that of the last 7 numbers is 48. If the 7^th number is excluded, then what is the average of the remaining 12 numbers? 
1. 40.8
2. 38.6
3. 42.6
4. 36.4
5. 30.8

Answer 1

Correct Answer - Option 1 : 40.8

Given:

Average of 13 numbers = 42

Average of first 7 numbers = 38

Average of last 7 numbers = 48

Formula used:

Average = sum of observations/total number of observations

Calculation:

Sum of 13 numbers = 13 × 42 = 546

Sum of first 7 numbers = 7 × 38 = 266

Sum of last 7 numbers = 7 × 48 = 336

7^th number = 266 + 336 - 546 = 56

Required average = (546 - 56)/12 ≈ 40.8

∴ The average is 40.8