Monthly demand at a local auto parts store for automobile batteries is shown in the table below:

a. Using a simple (single) exponential smoothing model (with α = 0.15), determine the forecast for consumption in (1) month 25 and (2) month 30.

b. Do the same using the Winters seasonal smoothing model with αHW = 0.20, βHW = 0.05, and γHW = 0.10. Use the first year of data for initialization purposes.

c. Plot the demand data and the two sets of forecasts roughly to scale. Discuss your results briefly.