Please provide correct solutions with step-by-step workings/explanations.

Based on the AIC criteria, we select the ARMA(2,0) model using the detrended time series. The second order polynomial model is given by Y = 11.22 - 177.82t + 265t' + Xt. where X, is an ARMA(2,0). Table 1 shows the estimated ARMA model: Mean Estimate 0.9541 -0.3074 -0.0111 s.e. 0.0975 0.0979 0.1865 Table 1: Estimated ARMA ModelCross-covariances are symmetric in k : cov (yit, yit-k ) = cov (yit, yittk ) when i = j