Year Quarter Sales

1 1 826

1 2 480

1 3 725

1 4 436

2 1 1041

2 2 773

2 3 876

2 4 545

3 1 1135

3 2 952

3 3 1141

3 4 727

A retail store sells space heaters. Sales data for space heaters is above

a. Plot the time series. Describe the time series in a few sentences.

b.Calculate the seasonal index for each quarter. What are the implications of these indexes?

c. Calculate the trend equation for this data. Explain what the slope and intercept mean in

this context.

d. Using the multiplicative decomposition method calculate forecasts for each quarter of Year 4.