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
7th number = 266 + 336 - 546 = 56
Required average = (546 - 56)/12 ≈ 40.8
∴ The average is 40.8