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“unfair� coin

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by uptowngirl92 » Mon Nov 02, 2009 4:51 am
The probability is 0.6 that an "unfair" coin will turn up tails on any given toss. If the coin is tossed 3 times, what is the probability that at least one of the tosses will turn up tails?



Where's my error:
P(1)+P(2)+P(3)
6/10.4/10.4/10 + 6/10.6/10.4/10 +6/10.6/10.6/10
=0.516
:(
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by NikolayZ » Mon Nov 02, 2009 5:15 am
Hm, i think it's more convinient to use the (1-x) shortcut.
What is the probability that NO TAILs will appear on each of a three tosses?
It is 0.4*0.4*0.4=0.064
Then the probability that there will be a least 1 tail is : 1-0.064=0.936 - is this one is right ?
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Re: “unfair� coin

by xcusemeplz2009 » Mon Nov 02, 2009 6:41 am
uptowngirl92 wrote:The probability is 0.6 that an "unfair" coin will turn up tails on any given toss. If the coin is tossed 3 times, what is the probability that at least one of the tosses will turn up tails?



Where's my error:
P(1)+P(2)+P(3)
6/10.4/10.4/10 + 6/10.6/10.4/10 +6/10.6/10.6/10
=0.516
:(
the problem in your approach is that u are not considering the case of hth,hht,htt,tht

cal for this u will get the ans.
It does not matter how many times you get knocked down , but how many times you get up
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