[6]3.Let yi=0+a 1': 1,2,...,m and yi=51+a i=m+1,...,m+n where ...d 61,. ..,6m+n ti" N(0,0'). Use the least squares method to find estimators for fig and til. Are these estimators unbiased? Find an unbiased estimator for 0'2. Calculate the distribution for 31 30