Question

Mean and variance of 10 observations are 15 and 4. If one observations was taken as 12 instead of 21. Find correct mean and standard deviation.​

Answer 1

Given: Mean of 10 numbers = 15

So sum of all numbers = 15×10

150

Now, 12 is taken in place of 21

So right sum = 150 - 12 + 21

= 159

So currect mean will be = 159/10

=15.9

Standard deviation = √variance

= √4

= 2

So correct mean is 15.9 and standard deviation is 2.