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.
Choices:  A) 151  B) 149  C) 152  D) 251  E) None of the above
Corrected mean = 250×30−135+165/30   = 7500−135+165/30   =7530/30= 
<gadget id="calculator">7530/30</gadget>
<output>251</output>
251   Answer 251
<result>D</result>
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.