Sales ($1,000s) Month Sales ($1,000s) Month

11 January 14 August

14 February 17 September

16 March 12 October

10 April 14 November

15 May 16 December

17 June 11 January

11 July

a)Using a moving average with three periods, determine the demand for vacuum cleaners for next February.

b)Using a weighted moving average with three periods, determine the demand for vaccum cleaners for February. Use 3, 2, and 1 for the weights of the most recent, second most recent, and third most recent periods, respectively. For example, if you were forecasting the demand for February, November would have a weight of 1, December would have a weight of 2, and January would have a weight of 3.

c)Evaluate the accuracy of each of these methods using MAD.

d)What other factors might R. Lowenthal consider in forecasting sales?