Problem 3: Consider the following AR(1) process yt = 0.7 - 0.8yt-1 + Et . Compute the mean, variance, covariance and Autocorrelation function (ACF).. Is the AR(1) process stationary and invertible? Why? . Simulate 200 observations from the processes and discard the initial 100 observations. (don't use arima.sim function in R ) . Simulate 100 observations from each of these processes (use arima.sim function in R). Com- pute their sample Autocorrelation functions up to lag 10 and observe that they exhibit the same pattern