Barbara Lynch, the product manager for a line of skiwearproduced by HeathCo Industries, has been working on developingsales forecasts for the skiwear that is sold under the NorthernSlopes and Jacque Monri brands. She has had variousregression-based forecasting models developed. Quarterly sales for1988Q1 through 1997Q4 are as follows:

	Sales
Year	Q1	Q2	Q3	Q4
1988	72,962	81,921	97,729	142,161
1989	145,592	117,129	114,159	151,402
1990	153,907	100,144	123,242	128,497
1991	176,076	180,440	162,665	220,818
1992	202,415	211,780	163,710	200,135
1993	174,200	182,556	198,990	243,700
1994	253,142	218,755	225,422	253,653
1995	257,156	202,568	224,482	229,879
1996	289,321	266,095	262,938	322,052
1997	313,769	315,011	264,939	301,479

a) Prepare a time-series plot of the data, and on the basis ofwhat you see in the plot, write a brief paragraph in which youexplain what patterns you think are present in the salesseries.

b) Smooth out seasonal influences and irregular movement bycalculating the center moving averages. Add the centered movingaverages to the original data you plotted in part a. Has theprocess of calculating center moving averages been effective insmoothing out the seasonal and irregular fluctuations in the data?Explain.

c) Determine the degree of seasonality by calculating seasonalindexes for each quarter of the year.

d) Develop a forecast for Ms Lynch for the four quarters of1998.