Correct Answer - Option 4 : 67.7
Given:
Actual average marks of the 50 students = 68
The incorrect marks = 83 and 64
The correct marks = 38 and 94
Formula Used:
Average = Sum of all the observations/Total number of observations
Calculation:
Initial total marks = 50 × 68 = 3400
Difference between the correct and the incorrect marks = (38 - 83) + (94 - 64)
⇒ -45 + 30 = -15
Hence, the actual total marks = 3400 – 15 = 3385
Also, the actual average marks = 3385/50 = 67.7
∴ The correct average marks is 67.7