A Note We may note that adding (or subtracting) a positive number to (or from) each observation of a group does not affect the variance. Example The mean and standard deviation of observations were calculated as and . , respectively by a student who took by mistake instead of for one observation. What are the correct mean and standard deviation?
Solution Given that number of observations ( n ) = Incorrect mean ( x ) = , Incorrect standard deviation ( σ ) = . We know that