the final answer please

A manager has been using a certain forecasting technique to forecast demand for word processing units for the past five periods. Actual and forecasted amounts are shown below. He had difficulties in identifying whether the used technique is better than the weighted moving average WMA) with 0.5 being the welght with the most recent, 0.3, 0.2. D) Calculate the MAD for the WMA forecast? (Note: write the answer as a number with 2 decimal places only, e.g. 12,50.55.83. 12.00) Period Demand forecasted 90 1 2 3 4 5 85 91 92 95 98 87 95 7 88