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प्रश्न
A dice is thrown thrice. A success is 1 or 6 in a throw. Find the mean and variance of the number of successes.
उत्तर
Here, n =3
\[\text{ p }= \text{ probability of getting } \ 1 \ \text{ or }\ 6 = \frac{1}{3}\]
\[\text{ and } \text{ q }= 1 - \frac{1}{3} = \frac{2}{3}\]
\[\text{ Mean } = \text{ np }= 1\]
\[\text{ Variance } = \text{ npq }= \frac{2}{3}\]
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