PM Computer Services assembles customized personal computers from generic parts. The

company was formed and is operated by two part$-$time university students, Paul and Bryan. The

company has experienced steady growth since started. The computer parts are bought using

volume discounts when good deals can be found. As such it is important that they develop a good

model to forecast demand for their computers so that they will know how many computer

components parts to purchase and stock.

The company has accumulated computer demand data over a $12-$month period. The data are shown

in the worksheet named PM$.$