Math Is Fun Forum

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Probability, 2 fair coins

Hi all,

2 fair coins are flipped and atleast one of the outcomes is known to be a head., what is the probability that both outcomes are head?

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"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability, 2 fair coins

Hi;

Looks good to me!

If you want to get confused about this go here.

http://trickofmind.com/?p=439

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Probability, 2 fair coins

Hi bobbym,

Thanks for looking into it, and thanks for the link!

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"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability, 2 fair coins

Hi;

Just be careful some of those guys at that link are wrong.

Here is a pdf that you can download that covers the math and answers that question.

http://www.cse.buffalo.edu/~atri/course … lect4.pdf.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Probability, 2 fair coins

Hi,

yes, I verify before accepting any answer!
Thanks for this link too.

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"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Howardroark

Member

Registered: 2010-10-10

Posts: 382

Re: Probability, 2 fair coins

Hi gAr,

2 fair coins are flipped and atleast one of the outcomes is known to be a head., what is the probability that both outcomes are head?

You are right.. Here's a problem similar to yours..

A couple has 2 children. One of them is a girl. What is the probability that the other is a girl?

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I come from a civilization which has given the world the number 0..

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Probability, 2 fair coins

Hi Howardroark,

Thanks for looking into the problem.

---

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."