@Puneet: So are you saying that 100 heads in a row wouldn't convince
you that you had the unfair coin? How many heads in a row would it
take?

Dave

On Aug 7, 2:40 pm, Puneet Gautam <[email protected]> wrote:
> Sixth toss is independent of previous tosses and dependent only on
> coin selection...!
>
> 1/5 + 4/5(1/2)= 3/5
>
> is the correct answer....
>
> we want to calc. probability of getting heads the sixth time only....
> even if it would have been 100 th time...3/5 would be the answer
> only..
>
> On 8/8/11, Prakash D <[email protected]> wrote:
>
>
>
> > 1.) coin is fair
> > 2.) coin is unfair
>
> > P(head) for unfair coin= 1/5 * 1= 1/5
> > P(head) for fair coin= 4/5* 1/2 = 2/5
>
> > the probability at any instant that the tossed coin is a head is 3/5
>
> > 17/80 is the probability to get head at all the six times.
>
> > the soln. for this problem will be 3/5
>
> > On Mon, Aug 8, 2011 at 12:45 AM, aseem garg <[email protected]> wrote:
>
> >> If the coin is unbiased then probability of heads: 1/2 irrespective of
> >> whether it is first time or nth time. So answer should be 3/5.
> >> Aseem
>
> >> On Mon, Aug 8, 2011 at 12:39 AM, saurabh chhabra
> >> <[email protected]>wrote:
>
> >>> Even u dont get why u people are gettin 17/80...the probability that
> >>> it will be a head 6th time will be same as the frst time...so it shud
> >>> be 3/5...
>
> >>> On Aug 7, 11:05 pm, Kunal Yadav <[email protected]> wrote:
> >>> > @algo: We can get head in two cases:-
>
> >>> > 1.) coin is biases
> >>> > 2.) coin is not biased
>
> >>> > P(head) for biased= 1/5 *1*1*1*1*1*1= 1/5
> >>> > P(head) for unbiased= 4/5*(1/2)^6
> >>> > hence combined probability is what nitish has already mentioned. Hope
> >>> you
> >>> > get the point.
>
> >>> > On Sun, Aug 7, 2011 at 11:29 PM, Algo Lover <[email protected]>
> >>> wrote:
> >>> > > Can anyone explain the approach how to solve this .
> >>> > > I think all tosses are independent so it should be 3/5. why is this
> >>> in-
> >>> > > correct
>
> >>> > > On Aug 7, 10:55 pm, saurabh chhabra <[email protected]> wrote:
> >>> > > > sry...its wrong
>
> >>> > > > 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).
>
> >>> > > --
> >>> > > You received this message because you are subscribed to the Google
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>
> >>> > --
> >>> > Regards
> >>> > Kunal Yadav
> >>> > (http://algoritmus.in/)
>
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