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Re: coin toss
Posted:
Sep 5, 2005 1:34 PM


"Dave Chamberlain" <davec@osmium.mv.net> wrote in message news:dfgcri$2fls$1@pyrite.mv.net... > > Fakename <fakename@comcast.net> wrote: > > : If you toss 100 coins, what's the probability of getting 5 (either heads > or > : tails in a row)? 6 in a row? > : How do you figure it out? > > If I'm following the question correctly. > > Each toss has an equal chance 50/50 (1:2 or 1/2) of being heads or tails. > If the first toss is heads, the odds of the second toss still has > a 50/50 chance of being heads. > Tosses 1 and 2: > H H > H T > T H > T T > There are four combinations (2 choices raised to 2 tosses), with > 2 of them yielding all Heads or Tails. So your chances are > 2 out of the 4 combinations will be the same. 2/4 = 1/2 = 50% > > If you toss the coin a third time: > H H H > H H T > H T H > H T T > T H H > T H T > T T H > T T T > You wind up with 8 combinations, 2 raised to the 3rd power, with > 2 of those 8 being all the same. > > So if you were to toss it 5 times you would have 32 combinations, > 2^5 (64 combinations if you wanted 6 in a row). With 2 of them > being all the same. > With 5 coins: 2:32 = 1:16 = 6.25% > With 6 coins: 2:64 = 1:32 = 3.125% > >
No, what I mean is ...if you tossed the coin exactly 100 times, what is the probability that you will get at least one run of five in a row (either heads or tails)? >  > > davec >  >
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