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Mean and variance of a random variable — MATHS STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSMean and variance of a random variable1 Mark
MCQ
The probability distribution of a discrete random variable $X$ is given below:
$\text{X}:$
$1$
$2$
$3$
$4$
$\text{P}(\text{X}):$
$\frac{1}{10}$
$\frac{1}{5}$
$\frac{3}{10}$
$\frac{2}{5}$
The value of $E(X^2)$ is:
  • A
    $3$
  • B
    $5$
  • C
    $7$
  • ✓
    $10$
✓

Answer

Correct option: D.
$10$
$\text{X}$ $1$ $2$ $3$ $4$  
$\text{P}(\text{X})$ $\frac{1}{10}$ $\frac{1}{5}$ $\frac{3}{10}$ $\frac{2}{5}$  
$\text{X}^2\text{P(X)}$ $\frac{1}{10}$ $\frac{4}{5}$ $\frac{27}{10}$ $\frac{32}{5}$ $\text{E}(\text{X}^2)=10$

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