试确定常数C,使P(X=i)=C/2(i=0,1,2,3,4)成为某个随机变量X的分布律,并求:P(X≤2);P(1/2

问题描述:

试确定常数C,使P(X=i)=C/2(i=0,1,2,3,4)成为某个随机变量X的分布律,并求:P(X≤2);P(1/2

∑P(X=i)=∑(C/2)=5C/2=1,C=2/5
P(X=i)=1/5(i=0,1,2,3,4)
P(X=i)=1/5(i=0,1,2,3,4)
P(X≤2)=P(X=0)+P(X=1)+P(X=2)=3/5;
P(1/2