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Question: Answered & Verified by Expert
The mean and variance of a random variable $\mathrm{X}$ having binomial distribution are 4 and 2 respectively, then $\mathrm{P}(\mathrm{X}=1)$ is
MathematicsProbabilityBITSATBITSAT 2021
Options:
  • A $\frac{1}{4}$
  • B $\frac{1}{32}$
  • C $\frac{1}{16}$
  • D $\frac{1}{8}$
Solution:
1904 Upvotes Verified Answer
The correct answer is: $\frac{1}{32}$
$\begin{aligned} n p &=4 \\ n p q &=2 \\ \Rightarrow q &=\frac{1}{2}, p=\frac{1}{2}, n=8 \\ \mathrm{P}(\mathrm{X}&=1)={ }^{8} \mathrm{C}_{1}\left(\frac{1}{2}\right)\left(\frac{1}{2}\right)^{7}=8 \cdot \frac{1}{2^{8}}=\frac{1}{2^{5}}=\frac{1}{32} \end{aligned}$

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