@Coder: You (and others) are saying that the probability of a head is 3/5 on the first flip, and that it doesn't change after any number of heads are flipped. Notice, however, that if the first flip were tails, you wouldn't say that the probability of getting heads on the next flip is 3/5. You would have learned that one of the four fair coins was chosen. So even though the probability of a head was 3/5 on the first flip, it changes to 1/2 on all flips subsequent to a tail. Since the probabililty changes if a tail is flipped, what makes you think it doesn't change if a head is flipped.
In fact, the probability is 3/5 for the first flip. After a head is flipped, the probability of a head is 2/3. After two heads have been flipped, it is 3/4. After 3 heads, it is 5/6. After 4 heads, the probability is 9/10, and after 5 heads, the probability is 17/18. Dave On Aug 8, 11:23 pm, coder dumca <coder.du...@gmail.com> wrote: > it's 3/5 > > > > On Tue, Aug 9, 2011 at 8:29 AM, Dave <dave_and_da...@juno.com> wrote: > > @Dipankar: You are correct about the answer to your alternative > > question being 17/80, but your answer 3/5 says that you don't think > > you have learned anything by the five heads flips. Don has given a > > good explanation as to why the answer is 17/18, but you apparently > > refuse to accept it. There is none so blind as one who will not see. > > > Dave > > > On Aug 8, 9:26 pm, Dipankar Patro <dip10c...@gmail.com> wrote: > > > 3/5. > > > > As the question doesn't ask anything about the sequence. > > > Had the question been " Find the probability that all 6 are H " then it > > > would have been 17/80. > > > > On 9 August 2011 04:07, Dave <dave_and_da...@juno.com> wrote: > > > > > @Vinay: What if you tossed 100 consecutive heads? Would that be enough > > > > to convince you that you had the double-headed coin? If so, then > > > > doesn't tossing 5 consecutive heads give you at least an inkling that > > > > you might have it? Wouldn't you then think that there would be a > > > > higher probability of getting a head on the sixth toss than there was > > > > on the first toss (3/5)? Don's conditional probability answer 17/18 is > > > > the right answer. > > > > > Dave > > > > > On Aug 8, 5:04 pm, vinay aggarwal <vinayiiit2...@gmail.com> wrote: > > > > > answer should be 3/5 > > > > > think like that tossing 5 times will not help you predict the outcome > > > > > of sixth toss. Therefore that information is meaningless. > > > > > -- > > > > 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. > > > > -- > > > ___________________________________________________________________________________________________________ > > > > Please do not print this e-mail until urgent requirement. Go Green!! > > > Save Papers <=> Save Trees > > > -- > > 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. -- 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.
