(a) Compute four-week and five-week moving averages for the time series. Week Time Series Value 4-Week Moving Average Forecast 5-Week Moving Average Forecast 1 18 2 21 3 19 4 24 5 18 20.5 6 17 20.5 7 21 19.5 8 19 20 9 22 18.75 10 20 19.75 11 15 12 22 (b) Compute the MSE for the four-week moving average forecasts. (Round your answer to two decimal places.) Compute the MSE for the five-week moving average forecasts. (Round your answer to two decimal places.) (c) What appears to be the best number of weeks of past data (three, four, or five) to use in the moving average computation? MSE for the three-week moving average is 10.31. Three weeks appears to be best, because the three-week moving average provides the smallest MSE. Three weeks