Question
The random variable $X$ has a probability distribution $P(X)$ of the following form, where k is some number :$ \text{P}(\text{X}) = \begin{cases} \text{k, }\overline{\text{if}\ \text{x}=0} \\ \overline{ 2\text{k, }\text{if}\ \text{x}=1}\\3\text{k, }\text{if}\ \text{x}=2\\0,\ \text{otherwise} \end{cases}$
  1. Determine the value of $k.$
  2. Find $P(X < 2), P(X ≤ 2), P(X ≥ 2).$

Answer

Probability distribution:
$x_i$ $0$ $1$ $2$
$P(x_i)$ $k$ $2k$ $3k$
  1. $P(X = 0) + P(X = 1) + P(X = 2) = 1$
$\Rightarrow k + 2k + 3k = 1 $
$\Rightarrow 6k = 1$
$\Rightarrow\ \text{k}=\frac{1}{6}$
  1. $P(X < 2) = P(X = 0) + P(X = 1)$
$=\text{k}+2\text{k}=3\text{k}=3\times\frac{1}{6}=\frac{1}{2}$
$P(X \geq 2) = P(X = 2) = 3k $
$=3\times\frac{1}{6}=\frac{1}{2}$
 

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free