19. Time-series forecasting may be used to predict future values of a variable by: a. A simple moving average c. Exponential smoothing b. A weighted moving average d. All of the above 76 20. Given the following data: Period: 1 # sold: 66 2 62 70 60 6 72 7 68 8 78 00aWN The estimate of the number sold for the 9th period using a simple moving average and k= 4 is: a. 73.00 b. 69.50 d. 71.92 Ic. 78