A major source of revenue in Texas is a state sales tax on certain types of goods and services. Data are compiled and the state comptroller uses them to project future revenues for the state budget. One particular category of goods is classified as Retail Trade. Four years of quarterly data (in $millions) for one particular area of southeast Texas follow:

Quarter	Year 1	Year 2	Year 3	Year 4
1	205	213	219	228
2	231	236	244	256
3	237	246	258	265
4	274	282	296	307

a) Compute seasonal indices for each quarter based on a CMA (centered moving average).

b) Deseasonalize the data and develop a trend on the deseasonlized data.

c) Use the trend line to forecast the sales for each quarter of year 5.