41. The weekly demand (in cases) for a particular brand of automatic dishwasher detergent for a chain of grocery stores located in Columbus, Ohio, follows.

Week Demand Week Demand

1 22 6 24

2 18 7 20

3 23 8 19

4 21 9 18

5 17 10 21

a. Construct a time series plot. What type of pattern exists in the data?

b. Use a three-week moving average to develop a forecast for week 11.

c. Use exponential smoothing with a smoothing constant of