Question 2 An alternative to Welch's t-method is the "pooled variance" t-method where we assume that the model variances are the same: X1 . . . . . Xm - N(/1, 62) Yl, . . . . Yn ~ N(12. 02) We know the usual sample variances So and S, are both unbiased estimators of of. Consider $2 = (m-1)5 +(-1)s; men-2 Show that So is an unbiased estimator of of