Forecasting with moving Average: Foa a given time series of sales, the training period consists of 50 months. The first 5 months of data are shown below :

Month Sales Sep98 27 Oct98 31 Nov98 58 Dec98 63 Jan99 59

a. compute the sales forecast for January 1999 based on a moving average model with span w=4(looking for the RStudio's code) b. Compute the forecast error for the above forecast(looking for the RStudio's code)