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Assuming steps are +1/-1 with a 50/50 probability. What is the expected step count for reaching 10, 100 or K?

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Answer: +Infinity. –  Did Feb 17 '13 at 20:26
    
But even though it takes infinite time on average, it still happens sooner or later with probability 1. –  Henning Makholm Feb 17 '13 at 20:50
    
Why not answer in the answers with a proof or a link to a proof? –  ubershmekel Feb 18 '13 at 12:59
    
Because you do not play along the rules of the site. –  Did Feb 27 '13 at 8:08

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