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key probablity

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P(Successful try) = 1/n
P(Unsuccessful try) = 1- 1/n 

Success will be in nth try i.e. n-1 Unsuccessful try must be there.
P(Success in nth try) = (1-1/n)(1-1/n)(1-1/n).........n times * 1/n =((n-1)/n)n-1 *1/n


#If question is like LOCK will be opened in Atmost n try then,
1- (1-1/n)n = 1 - ((n-1)/n)n

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