[20 marks] Let X1,X2,,X10 be identically and independently distributed Normal random variables with mean 3 and variance 12 . Suppose that Y1=61i=10XiY2=41i=710Xi a. What is the distribution of Y1 ? b. What is the distribution of Y2 ? c. If (Y1Y2)2/B has a X12 distribution, determine the value of B..