Re: I don't know Python, but I think I know what went wrong there.
Tor Send a noteboard - 25/05/2010 01:53:01 PM
I'll try again. This time without python.
You throw two coins 1000 times. Each time, you write down the result. On average, you will then get roughly 250 heads-heads, 250 tails-tails, 250 heads-tails and 250 tails-heads. I hope we all agree on this.
You then select one of those results you just wrote down, and tell your friend that at least one of the coins came up heads in that throw. What is the probability that the other coin was also heads?
Well, since one of the coins was heads, you can disregard all the tails-tails results. That means that you could have one of the 250 heads-tails results, or one of the 250 tails-heads results, or one of the 250 heads-heads results. Hence, the probabilty that it was heads-heads is only 1/3.
Also, I don't know why this is relevant, but to get 1/3 from powers of 2, you can take (1/2^2)
1-1/2^2). Which is essentially what we are doing here.
You throw two coins 1000 times. Each time, you write down the result. On average, you will then get roughly 250 heads-heads, 250 tails-tails, 250 heads-tails and 250 tails-heads. I hope we all agree on this.
You then select one of those results you just wrote down, and tell your friend that at least one of the coins came up heads in that throw. What is the probability that the other coin was also heads?
Well, since one of the coins was heads, you can disregard all the tails-tails results. That means that you could have one of the 250 heads-tails results, or one of the 250 tails-heads results, or one of the 250 heads-heads results. Hence, the probabilty that it was heads-heads is only 1/3.
Also, I don't know why this is relevant, but to get 1/3 from powers of 2, you can take (1/2^2)
1-1/2^2). Which is essentially what we are doing here.
Fram kamerater!
Recreational mathematics
- 24/05/2010 09:17:27 PM
1284 Views
How is boy/girl different from girl/boy?
- 25/05/2010 01:05:15 AM
1250 Views
I think it has to do with sequence
- 25/05/2010 08:37:05 AM
1010 Views
The problem doesn't state the sequence, so there's no reason to assume it.
- 25/05/2010 08:56:09 AM
1094 Views
Faulty "logic". 2/4
- 25/05/2010 02:12:54 AM
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I was going to say.
- 25/05/2010 02:48:38 AM
1029 Views
Yeah
- 25/05/2010 05:05:16 AM
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Re: Yeah
- 25/05/2010 09:52:58 AM
1372 Views
I don't know Python, but I think I know what went wrong there.
- 25/05/2010 11:33:18 AM
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Re: I don't know Python, but I think I know what went wrong there.
- 25/05/2010 01:53:01 PM
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Ah, I see now; sorry.
- 25/05/2010 02:27:05 PM
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You realize this thread now contains the words "Monty" and "Python" several times, right? 
- 26/05/2010 11:01:24 AM
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- 26/05/2010 11:01:24 AM
908 Views