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प्रश्न
Five cards are drawn successively with replacement from a well-shuffled pack of 52 cards. What is the probability that none is a spade ?
उत्तर
Let X denote the number of spade cards when 5 cards are drawn with replacement. Because it is with replacement,
X follows a binomial distribution with n = 5; \[p = \frac{13}{52} = \frac{1}{4}; q = 1 - p = \frac{3}{4}\]
\[ = ^{5}{}{C}_0 \left( \frac{1}{4} \right)^0 \left( \frac{3}{4} \right)^5 \]
\[ = \frac{243}{1024}\]
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