The following time series shows the sales of a particular product over the past 12 months. Month Month 1 2 3 4 5 6 Sales 105 135 120 105 90 120 7 8 9 10 Sales 145 140 100 80 100 110 11 12 a. Construct a time series plot. What type of pattern exists in the data? b. a Use a = 0.3 to compute the exponential smoothing values for the time series. Use trial and error to find a value of the exponential smoothing coefficient a that results in a relatively small MSE. c