The table below shows the demand for a particular brand of fax machine in a department store in each of the last twelve months.

Month 1 2 3 4 5 6 7 8 9 10 1 12

Demand 12 15 19 23 27 30 32 33 37 41 49 58

a. Calculate the four month moving average for months 4 to 12. What would be your forecast for the demand in month 13?

b. Apply exponential smoothing with a smoothing constant of 0.2 to derive a forecast for the demand in month 13.

c. Which of the two forecasts for month 13 do you prefer and why?

d. What other factors, not considered in the above calculations, might influence demand for the fax machine in month 13?