Mathematics Part-II

Book: Mathematics Part-II

Chapter: 13. Probability

Subject: Maths - Class 12th

Q. No. 9 of Exercise 13.5

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On a multiple choice examination with three possible answers for each of the five questions, what is the probability that a candidate would get four or more correct answers just by guessing ?

In this question, we have the repeated correct answer guessing form the given multiple choice questions are Bernouli trials

Let us now assume, X represents the number of correct answers by guessing in the multiple choice set

Now, probability of getting a correct answer,


Clearly, we have X is a binomial distribution where n = 5 and

Hence, probability of guessing more than 4 correct answer

= P (X = 4) + P (X = 5)


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