The sum of 30 observations is 910. If one of the observations is taken as -25 instead of 25, find the correct mean.
Correct answer: C
Explanation
The wrong sum is 910 because one value was recorded as -25 instead of +25, an error of 50. Adding the difference back gives the correct sum of 910 + 50 = 960. Dividing by 30 observations gives a correct mean of 960 / 30 = 32.