Q11 of 46 Page 1

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

This question is based on Bernoulli’s distribution.


Here the experiment is to get 4 or more correct answers by guessing n=5 questions.


There are three possible answers, P(getting correct answer)


⇒


And P(getting wrong answer)


⇒


Let X be the number of correct answers, then


⇒ where x=0,1,….,n. and p+q=1


Now we have to calculate


P(getting 4 or more correct answers)=P(4)+P(5)


⇒


⇒


⇒


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