The average marks of 14 students was 71. It was later found that the marks of one of the student has been wrongly entered as 42 instead of 56 and another as 74 instead of 32. What is the correct average ?

Answer: Option D

According to the question,
Wrong marks = 42 + 74 = 116
Correct marks = 56 + 32 = 88
Difference = 116 - 88 = 28 marks
∵ This difference effect the 14 students = $$\frac{28}{14}$$ = 2
And, incorrect average = 71
∴ Correct average = 71 - 2 = 69