Please show me how to do this step by step using excel !

Problem 1 Given below are the monthly actual sales of Wangdoodles for December of one year and the first six months of the following year. Also given are three sets of forecast numbers: 0 F(l): the Na'ive (last period) technique. 0 F(2): a simple exponentially smoothed average with or = 0.20. o F(3): a three-month moving average mm F(s) m _ ___- ___- ___- 1. Fill in July's forecasted sales for F(l), F(2) and F(3), using each of the three forecasting methods. 2. Which of the three forecasting methods is best for the given data? Why? 3. For forecast 2, F(2), is a smoothing constant of 0.2 or 0.3 better for the sales data? Explain. Note : For questions 2 and 3, since this is a practice problem, use all forecast accuracy measures (MAE, MSE and MAPE) learned in chapter 8