The mean of 30 values was 250. It was detected on rechecking that one value 165 was wrongly copied as 135 for the computation of the mean. Find the correct mean.  Pick one:
A) 151  B) 149  C) 152  D) 251  E) none of the above

Rationale: "corrected mean = 250 × 30 − 135 + 165 / 30 = 7500 − 135 + 165 / 30 = 7530 / 30 = 251 answer d"
Answer: D