1 1 vote A man with n keys wants to open a lock. He tries his keys at random. The expected number of attempts for his success is (keys are replaced after every attempt) a) n/2 b) n c) √ n d) None of the above Probability isro-ece engineering-mathematics expectation + – sh!va 4.1k views answer comment Share Follow Print See all 21 Comments 21 21 Comments reply Show 18 previous comments sushmita commented Mar 3, 2017 reply Follow flag here we are asked number of trials and whenever no of trails are asked it is geometric distribution. 0 0 replyShare Rahul Jain25 commented Mar 3, 2017 reply Follow flag Thanks @sushmita. https://en.wikipedia.org/wiki/Geometric_distribution?wprov=sfla1 0 0 replyShare Akriti sood commented Mar 3, 2017 reply Follow flag @sushmita,is it true in every case?? 0 0 replyShare Please log in or register to add a comment.