a. Using a weight of 1/2 for the most recent observation, 1/3 for the second most recent, and 1/6 for third most recent, compute a three-week weighted moving average for the time series. Use rounded for two decimal places values for intermediate calculations. Use minus sign for negative values. Weighted Moving Average Forecast Forecast Error (Error)? Week Sales 1 17 2 24 3 20 4 25 20.83 4.17 17.36 X 5 19 23.17 -4.17 17.36 x 6 18 21.17 -3.17 10.03 x 7 21 19.50 1.50 2.25 8 17 19.67 -2.67 7.11 x 9 22 18.50 3.50 12.25 10 20 20.17 -0.17 0.03 11 13 20.17 -7.17 51.36 X 12 21 16.38 X -4.17 X 17.36 X Total 135.11 x b. Compute the MSE for the weighted moving average in part a. Do you prefer this weighted moving average to the unweighted moving average? Remember that the MSE for the unweighted moving average is 10.22. Round your answer to two decimal places. MSE = 15.01 x