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Originally Posted by Dkumar
Hi Brinda!
I get a different answer for your question.
On any day in April in a certain city, the probability of rain is 50%. What is the probability of that it rains exactly 5 days during a 7 day period in April?
Acc to my calculation,
Probability that it will rain in a any day is 1/2
Prabability that it will not rain is (1-1/2) = 1/2
Probability that it will rain exactly 5 days and will not rain the other two days = 1/2 *1/2*1/2*1/2*1/2*1/2*1/2 = 1/128
Please let me know the correct answer.
Thanks.
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Kumar,you have to use the binomial method here.
nCr(p)^r(q)^n-r
so here its
7C2(50/100)5(50/100)2
which is
21(1/2)^7