If the p.m.f. of a discrete random variable $X$ is $P(X=x)=\frac{c}{x^3}$, $x=1,2,3=0$, otherwise then $E(X)$ is equal to

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Aicharya · Accepted Answer

$\begin{aligned} & \because \sum P_i=1 \ & \Rightarrow \frac{251}{216} C \ & \Rightarrow C=\frac{216}{251} \ & 	ext { now } E(x)=\sum p_i x_i=\frac{49}{36} C=\frac{49}{36} 	imes \frac{216}{251}=\frac{294}{251}\end{aligned}$

If the p.m.f. of a discrete random variable $X$ is $P(X=x)=\frac{c}{x^3}$, $x=1,2,3=0$, otherwise then…

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