RE: Calculating odds.

[Ian Skinner]

Yeah, after reading all the posts here 6 or 7 or eight times, I think I got it. 
 I was hung up on, "but how do you know the first card is GOOD".  I think a dim 
light bulb went of, and the answer, as I believe you put it Ben, is if the card 
is not "GOOD" then the series as failed, voila.

Thanks for all the help.  I'm going to look at Larry's links, but I have a 
strong feeling his definition of basic statistics and my definition are to 
completely different levels by several magnitudes.

--------------
Ian Skinner
Web Programmer
BloodSource
www.BloodSource.org
Sacramento, CA

"C code. C code run. Run code run. Please!"
- Cynthia Dunning



...-----Original Message-----
...From: Ben Doom [mailto:[EMAIL PROTECTED]
...Sent: Friday, January 14, 2005 2:17 PM
...To: CF-Community
...Subject: Re: Calculating odds.
...
...Let's do a 5/10 half-size example.
...
...Good cards: 1,2,3,4,5
...Bad cards:  a,b,c,d,e
...
...First card drawn is 1
...Good cards left:  2,3,4,5
...Bad cards left:   a,b,c,d,e
...Total cards left: 9
...
...Now, for your second draw, there are 4 good cards left, and 9 total
...cards, so the chances of the next card drawn being good is 4/9.
...
...Cards drawn:      1,2
...Good cards left:  3,4,5
...Bad cards left:   a,b,c,d,e
...Total cards left: 8
...
...Now, there are only 3 good cards left.  The chances of the next draw
...being good is 3/8.
...
...Making more sense?
...
...--Ben
...
...
...
...Ian Skinner wrote:
...> I'm sorry, but this is just bouncing off of my thick skull and getting
...lost in space.
...>
...> You've removed a "good" card from the possibilities.  For the first
...one,
...> there are 10 good cards and 20 total.  For the second, there are 9 good
...> cards and 19 total.  And so forth.
...>
...> --Ben
...>
...> How have you removed a good card if this is being calculated before any
...cards are drawn?  Is this just the way of statistics?
...>
...>
...> --------------
...> Ian Skinner
...> Web Programmer
...> BloodSource
...> www.BloodSource.org
...> Sacramento, CA
...>
...> "C code. C code run. Run code run. Please!"
...> - Cynthia Dunning
...>
...>
...>
...> ...-----Original Message-----
...> ...From: Ben Doom [mailto:[EMAIL PROTECTED]
...> ...Sent: Friday, January 14, 2005 12:29 PM
...> ...To: CF-Community
...> ...Subject: Re: Calculating odds.
...> ...
...> ...You've removed a "good" card from the possibilities.  For the first
...one,
...> ...there are 10 good cards and 20 total.  For the second, there are 9
...good
...> ...cards and 19 total.  And so forth.
...> ...
...> ...--Ben
...> ...
...> ...Ian Skinner wrote:
...> ...> Draw 5 numbers from Set B = 10/20 * 9/19 * 8/18 * 7/17 * 6/16.
...> ...>
...> ...> Ok, I was going 10/20 * 10/19 * 10/18 * 10/17 * 10/16.
...> ...>
...> ...> Can you refresh my very rusty statistics on why both the numerator
...and
...> ...denominator are reduced for each iteration?
...> ...
...> ...
...> ...
...>
...>
...
...

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