F I L E following data represent a portion of quarterly net sales (in millions of dollars) of Lowe's Companies, Inc., over the past five years; the full data set can be found on the text website, labeled Lowe's Net Sales.

Year Quarter 1 Quarter 2 Quarter 3 Quarter 4 2004 $8,861 $10,169 $9,064 $8,550 2005 9,913 11,929 10,592 10,808 ⋮ ⋮ ⋮ ⋮ ⋮
2008 12,009 14,509 11,728 9,984 SOURCE: All data retrieved from Annual Reports for Lowe's Companies, Inc.

a. Estimate a linear trend model with seasonal dummy variables and compute the MSE and MAD.

b. Estimate an exponential trend model with seasonal dummy variables and compute the MSE and MAD.

c. Which model is more appropriate? Use this model to forecast net sales for Lowe's Companies, Inc., for fiscal year 2009.