Question

The mean of 40 numbers was found to be 38. Later on, it was detected that the number 56 was misread as 36. Find the correct mean of the given numbers.

Answer 1

Given mean of 40 numbers = 38
Sum of 40 numbers = $38\times 40=1520$
Correct sum of 40 numbers = $1520-36+56$ =1540
So, correct mean of 40 numbers = $\frac{1540}{40}=38.5$