4. A major department store chain is having an end-of-season sale on refrigerators. The number of refrigerators sold during this sale at a sample of 10 stores was:

80 110 0 40 70 80 100 50 80 30

a. Compute the mean, mode, and median. Which measure of central tendency is most appropriate in this case and why?

b. Compute the variance and the standard deviation.

c. Construct a histogram, and discuss whether this variable is normally distributed.