4. The following data are monthly sales of jeans at a local department store. The buyer would like to forecast sales of jeans for the next month, July. (a) Forecast sales of jeans for March through June using the nave method, a two-period moving average, and exponential smoothing with an = 0.2. (Hint: Use nave to start the exponential smoothing process.) (b) Compare the forecasts using MAD and decide which is best. (c) Using your method of choice, make a forecast for the month of July.