Ms. Winnie Lin’s company sells computers. Monthly sales for a six-month period are as follows:

__________________

Month          Sales

^{__________________________}

Jan               18,000

Feb               22,000

Mar               16,000

Apr               18,000

May              20,000

Jun               24,000

a. Plot the monthly data on a sheet of graph paper.

b. Compute the sales forecast for July using the following approaches: (i) a three-month moving average; (ii) a weighted three-month moving average using .50 for June, .30 for May, and .20 for April.

c. Calculate the MAD for each of the two techniques in part b. Which is the best? Why?