Probability 5 Question 14

14. Numbers are selected at random, one at a time, from the two-digit numbers 00,01,02,,99 with replacement. An event E occurs if and only if the product of the two digits of a selected number is 18. If four numbers are selected, find probability that the event E occurs at least 3 times.

(1993,5 M)

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Answer:

Correct Answer: 14. 97254

Solution:

  1. Let E be the event that product of the two digits is 18 , therefore required numbers are 29,36,63 and 92 .

Hence, p=P(E)=4100

and probability of non-occurrence of E is

q=1P(E)=14100=96100

Out of the four numbers selected, the probability that the event E occurs atleast 3 times, is given as

P=4C3p3q+4C4p4=44100396100+4100=97254



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