Q4: Let X1, X2, ...,Xn1 be a random sample from a normal population with mean and variance , and Y1, Y2, . . ., Yn2 be a random sample from an independent normal population with mean and variance 2. Here = 2. Show that: X-Y-(-) (n1)S + (n1)S 1 n+n2-2 + n ~ T (m +n-2)