In a binomial distribution, if the mean is 6 and the standard deviation is \sqrt{2}, then what are the values of the parameters n and p respectively?
- A. 18 and 1/3
- B. 9 and 1/3
- C. 18 and 2/3
- D. 9 and 2/3 ✓
Correct Answer: D. 9 and 2/3
Explanation
For a binomial distribution, the mean is \mu = np = 6 and the variance is \sigma^2 = npq = (\sqrt{2})^2 = 2. Dividing the variance by the mean gives q = \frac{npq}{np} = \frac{2}{6} = \frac{1}{3}. Since p + q = 1, we have p = 1 - \frac{1}{3} = \frac{2}{3}. Substituting p back into the mean equation yields n(\frac{2}{3}) = 6, which solves to n = 9.
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