Question

The mean of 16 items was found to be 30. On rechecking, it was found that two items were wrongly taken as 22 and 18 instead of 32 and 28, respectively. Find the correct mean.

Answer 1

Given mean of 16 items = 30
Sum of 16 items = $16\times 30=480$
Correct sum of 16 items = $480-22-18+32+28$ = 500
So, correct mean of 16 items = $\frac{500}{16}=31.25$