Which of the following statements are correct? (A) The mean and variance of the Poisson distribution are equal. Choose the correct answer from the options given below: |
(A), (C) and (D) only (A) and (D) only (B), (C) and (D) only (A), (B) and (C) only |
(A), (C) and (D) only |
The correct answer is Option (1) → (A), (C) and (D) only ** (A) True. For Poisson distribution, mean = variance = $\lambda$. (B) False. For Binomial distribution, mean $=np$ and variance $=np(1-p)$ (equal only if $p=\frac12$). (C) True. Second six on 3rd throw means: First two throws → exactly one six, Third throw → six. Probability = $\frac{1}{6}\cdot\frac{5}{6}\cdot\frac{1}{6} + \frac{5}{6}\cdot\frac{1}{6}\cdot\frac{1}{6} = \frac{10}{216}=\frac{5}{108}$. This matches the given number, so (C) is True. (D) Variance = $\lambda = 2$. $P(X=2)=\frac{2^2 e^{-2}}{2!}=2e^{-2}$. True. Correct statements: (A), (C), (D) |