Question: International Dairy Queen, Inc., a firm whose business is highly seasonal, has reported the following quarterly net income figures for 1991 through 1995.

Net Income (Millions)

I II III IV

1991 155 231 270 105

1992 182 255 315 294

1993 160 250 280 297

1994 210 310 365 335

1995 225 325 384 386

a) Construct the four-quarter centered moving average for these data and determine the percentages of the moving average for the quarters.

b) Determine the seasonal indexes for the quarters.

c) Use the seasonal indexes to deseasonalize the original time series.