4.2.4. Suppose we assume that X1, X2, . . . , Xn is a random sample from a (1, ) distribution. (a) Show that the random variable (2/) n i=1 Xi has a 2 -distribution with 2n degrees of freedom. (b) Using the random variable in part (a) as a pivot random variable, nd a (1 )100% condence interval for . Hogg, Robert T; McKean, Joeseph; Craig, Allen T (2012-02-08). Introduction to Mathematical Statistics (7th Edition) (Page 219). Pearson HE, Inc.. Kindle Edition. Solution.