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Mr.IITIAN007 (2985)

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n persons have alloted seats while they take seats at random.What is the probability that
i) exactly k persons have found the alloted seats;
ii) at most k persons have found the alloted seats;
iii) at least p persons have found the alloted seats .

Ken
From: UNITED STATES, Green Bay, Wisconsin
    
aysh (673)

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1)If n no. of people sit randomly, they can sit in n! ways.
Out of these k no. of people sit in their alloted seats.
This means that (n-k) no. of people sit randomly.
No. of ways in which they sit in places other than the ones alloted to them
=(n-k-1)(n-k-2)....(1)=(n-k-1)!
Thus,
required probability=(n-k-1)! / n!

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Mr.IITIAN007 (2985)

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No aysh!!!!!!!
Actually I have the answer of the first part and it is (n-k-1)! / (2k4) but I don't know how it has come.I agree with you and I think some other cases in the problem have to be considered as well.Well please try!!!!!!!!!!!!!!!!!!!! for the ii) and iii).

Ken
From: UNITED STATES, Green Bay, Wisconsin
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