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by sheik » Wed Sep 15, 2010 7:31 pm
Hey guys having a problem with this one from the morning...would be great if you could help me out with this one....

A coin is tossed 12 times in succession . If the first 11 produce all tails . What is the probability that the 12th one will also be a tail. Each of the 12 tuple outcome is equally likely to occur..??
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by sanju09 » Wed Sep 15, 2010 8:00 pm
sheik wrote:Hey guys having a problem with this one from the morning...would be great if you could help me out with this one....

A coin is tossed 12 times in succession . If the first 11 produce all tails . What is the probability that the 12th one will also be a tail. Each of the 12 tuple outcome is equally likely to occur..??
If the first 11 tosses produce all tails, then their story is over and the 12th toss will be a fresh one, whose probability for an outcome of tail will be just 0.5.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
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The Princeton Review - Manya Abroad
Lucknow-226001

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by brijesh » Wed Sep 15, 2010 8:12 pm
A coin is tossed 12 times in succession . If the first 11 produce all tails . What is the probability that the 12th one will also be a tail. Each of the 12 tuple outcome is equally likely to occur..??[/quote]

lets add a few more Qs here:

A coin is tossed 12 times in succession . What is the probability of getting only one tail. Each of the 12 tuple outcome is equally likely to occur

A coin is tossed 12 times in succession. What is the probability of getting tail at 5th toss when all other toss gives head. Each of the 12 tuple outcome is equally likely to occur
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by sanju09 » Wed Sep 15, 2010 8:42 pm
brijesh wrote:lets add a few more Qs here:

(1) A coin is tossed 12 times in succession . What is the probability of getting only one tail. Each of the 12 tuple outcome is equally likely to occur

(2) A coin is tossed 12 times in succession. What is the probability of getting tail at 5th toss when all other toss gives head. Each of the 12 tuple outcome is equally likely to occur

(1) There are 12 ways of obtaining only one tail out of a total of 2^12 ways, probability = 12/2^12 = 3/2^10.

(2) When the results of all other throws except one are known, we don't really need to bother for these. Answer is still 0.5.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
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