2. Consider an MA(1) process for which it is known that the process mean is zero. Based on a series of length n = 3, we observe Y1 = 0, Y2 = -1, and Y3 = 1/2. Estimate 0 and of using the method of least squares. 3. Given the data Y1 = 10, Y2 = 9 and Y3 = 9.5, we want to fit an ARIMA (0,1,1 ) model without a constant term. Estimate 0 and of using the method of least squares