Question

The mean of 30 values was 150. It was detected on rechecking that one value 165 was wrongly copied as 135 for the computation of the mean. Find the correct mean.

• A. 151
• B. 149
• C. 152
• D. None of these

Answer 1

Answer: (A)

151

Answer 2

The mean of 30 values = 150

After replacing 135 by 165,

The correct mean will be = $\frac{30 \times 150 + (-135 + 165)}{30}$

= $150 + \frac{30}{30} = 151$

The correct mean will be 151

The correct option is (A): 151