Question

A random variable $X$ takes value $0,1,2$. Its mean is $1.3$. If $P(X=0)=0.2$, then $P(X=2)=$

• A. $0.3$
• B. $0.4$
• C. $0.5$
• D. $0.2$

Answer 1

Answer: (C)

$0.5$

Given Mean $=1.3,P(x=0)=0.2$

$0\times P(X=0)+1\times P(X=1)+2\times P(X=2)=1.3$

Let $P(X=2)=p$

$P(X=1)=1-P(X=0)-p=0.8-p$

Substituting in original equation

$P(X=1)+2P(X=2)=1.3$

$0.8-p+2p=1.3$

$p=0.5$