Sales figures (in units) for Bob's Blocks for the past five weeks have been as follows...Week 1: 1287, Week 2: 1431, Week 3: 1559, Week 4: 1623, Week 5: 1482, Week 6: 1503. Use a three-week moving average to forecast the Week 7 number of units sold. Also calculate the MAD for the forecasts. (Specifically, use the three-week moving average to forecast for weeks prior to Week 7 where possible, and then find the MAD).