Metro Food Vending operates vending machines in office buildings, the airport, bus stations, colleges, and other businesses and agencies around town, and it operates vending trucks for building and construction sites. The company believes its sandwich sales follow a seasonal pattern. It has accumulated the following data for sandwich sales per season during the past 4 years:

Develop a seasonally adjusted forecast model for these sandwich sales data. Forecast demand

for each season for year 5 by using a linear trend line estimate for sales in year 5. Do the data

appear to have a seasonal pattern?