Mean, and standard deviation of 100 observations was found to be 40 and 10 respectively. If at the time of calculation two observations were wrongly taken as 30 and 70 in place of 3 and 27 respectively, find the correct standard deviation.

Question

Philoid · Accepted Answer

Given, Uncorrected mean is 40 and corrected SD is 10 and N = 100

To Find: Find the correct mean and SD

Explanation: Here,

Then,

The corrected sum of observation

So,

Variance =100

10000+160000

Incorrect

Correct

Correct SD,

Hence, SD = 10.24