I'm little late but I too got 17/18. On Tue, Aug 16, 2011 at 10:47 PM, Jacob Ridley <[email protected]>wrote:
> I think there is some ambiguity in the question. > > >>> (All this time you don't know you were tossing a fair coin or not). > 1) Does the above statement mean that the thower don't know whether he > or she threw a fair coin even after throwing? Or is the thrower not > informed beforehand that one of them is not a fair coin? > 2) Does the coin count reduce after every throw or should it be put > back? > 3) Depending on 1) and 2), there will be different answers. > > > On Aug 9, 12:13 am, Maddy <[email protected]> wrote: > > 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 <[email protected]> wrote: > > > > > > > > > (3/5) > > > > > On Aug 7, 10:34 pm, Algo Lover <[email protected]> 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).- Hide quoted text - > > > > - Show quoted text - > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- regards, chinna. -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
