The Following Time Series Gives the Number of Units Sold

Essay

The following time series gives the number of units sold during 5 years at a boat dealership.
a. Find the four-quarter centered moving averages.
b. Plot the series and the moving averages on a graph.
c. Compute the seasonal-irregular component.
d. Compute the seasonal factors for all four quarters.
e. Compute the deseasonalized time series for sales.
f. Calculate the linear trend from the deseasonalized sales.
g. Forecast the number of units sold in each quarter of year 6.