Adding (or subtracting) the same number from each value in a set of data does not affect the measures of variability for that set of data.
a. Find the variance of this set of annual heating degree-day data: 6017, 6173, 6275, 6350, 6001, 6300.
b. Find the variance of this set of data (obtained by subtracting 6000 from each value in part a): 17, 173, 275, 350, 1, 300.