Assume that the trend line equation for the data of problem 16 is Yr = 1,244 +

4.53X, where X is each month in the series of data beginning with 1, 2, 3, etc.

a. Compute the average multiplicative seasonal index for each month of the year.

b. Compute the trend value for each of the next 6 months, and adjust each month’s trend value by the seasonal index.