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Question
If in a binomial distribution mean is 5 and variance is 4, write the number of trials.
Solution
\[\text{ Mean = 5 and Variance } = 4\]
\[ \Rightarrow \text{ np = 5 and npq } = 4 \]
\[ \Rightarrow q = 0 . 8 \]
\[ \Rightarrow p = 1 - q = 0 . 2\]
& np = n(0 . 2) = 5 (given)
\[ \Rightarrow n = \frac{5}{0 . 2} = 25\]
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