Q) Suppose a sample consisting of n=12 different data values has a mean of 5. One of the data values is -4 and another is 4.

a) A student calculates the sample variance of this sample and claims that S(squared) = 7.2. Explain why this value is incorrect.

b) If the two value -4 and 4 are removed what is the mean of the remaining data values?

Would much appreciate any help, not so much just the answers, but also how i get to them and the formulas used.

Thanks.