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A person has a bunch of n keys , only o...

A person has a bunch of n keys , only one of which exactly fits a lock . The person tries to open the lock by trying the keys at random . The probability that he opens the lock is at the kth attempt on the assumption that he rejects the keys already tried is :

A

k/n

B

1/n

C

`(k-1)/n`

D

None of these

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The correct Answer is:
B
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