I think the answer is 17/80, because as you say the 5 trials are independent.. but the fact that a head turns up in all the 5 trials, give some information about our original probability of choosing the coins.
in case we had obtained a tail in the first trial, we can be sure its the fair coin, and so the consecutive trials would become independent.. but since that is not the case, every head is going to increase the chance of choosing the biased coin(initially), and hence affect the probability of the next head.. before the first trial probability of landing a head is 3/5, but once u see the first head, the probability of landing a head on the second trial changes to 4/5*1/4+1/5, and so on..that is, there is a higher probability that we chose a biased coin, rather than the fair coin. hope its clear.. On Aug 7, 11:36 pm, sumit gaur <sumitgau...@gmail.com> wrote: > (3/5) > > On Aug 7, 10:34 pm, Algo Lover <algolear...@gmail.com> wrote: > > > > > > > > > A bag contains 5 coins. Four of them are fair and one has heads on > > both sides. You randomly pulled one coin from the bag and tossed it 5 > > times, heads turned up all five times. What is the probability that > > you toss next time, heads turns up. (All this time you don't know you > > were tossing a fair coin or not). -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
