5.30 For order statistics of a random sample of size N from any continuous population FX, show that the interval (X(r),X(Nrþ1), r < N=2), is a 100

(1a)% confidence-interval estimate for the median of FX, where 1  a ¼ 1  2N N  1 r  1

 ð 0:5 0

xNr(1  x)r1dx