Question

设离散型随机变量X的分布律为P{X=i}=K/2的i次,i=1,2,3,4,求K和P(X<=3)

Answer 1

由于∑P{X=i}=1，所以k(1/2+1/2^2+1/2^3+1/2^4)=15k/16=1，即k=16/15，所以P(X<=3)=1-P(X>3)=1-P(X=4)=1-(16/15)/16=14/15