Maharashtra State BoardHSC Arts 12th Board Exam
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Five cards are drawn successively with replacement from a well-shuffled deck of 52 cards, find the probability that none is a spade. - Mathematics and Statistics

Sum

Five cards are drawn successively with replacement from a well-shuffled deck of 52 cards, find the probability that none is a spade.

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Solution 1

Let X = number of spade cards.

p = probability of drawing a spade card from pack of 52 cards.

Since, there are 13 spade cards in the pack of 52 cards,

∴ p = `13/52 = 1/4  and  "q" = 1 - "p" = 1 - 1/4 = 3/4`

Given: n = 5

∴ X ~ B`(5, 1/4)`

The p.m.f. of X is given by

P(X = x) = `"^nC_x  p^x  q^(n - x)`

i.e. p(x) = `"^5C_x  (1/4)^x  (3/5)^(5 - x)`, x = 0, 1, 2,...,5

P(none of cards is spade) = P(X = 0)

= p(0) = `"^5C_0(1/4)^0(3/4)^(5 - 0)`

`= 1xx1 xx (3/4)^5 = 243/1024`

Hence, the probability of only 3 cards are spades = `243/1024`

Solution 2

Let X = number of spade cards.

p = probability of drawing a spade card from pack of 52 cards.

Since, there are 13 spade cards in the pack of 52 cards,

∴ p = `13/52 = 1/4  and  "q" = 1 - "p" = 1 - 1/4 = 3/4`

Given: n = 5

∴ X ~ B`(5, 1/4)`

The p.m.f. of X is given by

P(X = x) = `"^nC_x  p^x  q^(n - x)`

i.e. p(x) = `"^5C_x  (1/4)^x  (3/5)^(5 - x)`, x = 0, 1, 2,...,5

P(none is a spade)

= P(X = 0)

= `""^5"C"_0 (1/4)^0(3/4)^5`

= `(3/4)^5`.

Concept: Binomial Distribution
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APPEARS IN

Balbharati Mathematics and Statistics 2 (Commerce) 12th Standard HSC Maharashtra State Board
Chapter 8 Probability Distributions
Exercise 8.3 | Q 1.04 | Page 150
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