Probability 3 Question 42

42. Cards are drawn one by one at random from a well shuffled full pack of 52 playing cards until 2 aces are obtained for the first time. If N is the number of cards required to be drawn, then show that

PrN=n=(n1)(52n)(51n)50×49×17×13

where, 2<n50.

(1983, 3M)

Show Answer

Answer:

Correct Answer: 42. 0.6976

Solution:

  1. P(N th draw gives 2 nd ace )

=P1$aceand$(n2)$othercardsaredrawnin$(N1)$draws$×PN$thdrawis2ndace$

=4(48)!(n1)!(52n)!(52)!(n2)!(50n)!3(53n)=4(n1)(52n)(51n)352515049=(n1)(52n)(51n)50491713



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक