Subject:
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Re: math question (or pattern... whatever...)
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Mon, 3 Mar 2003 21:48:37 GMT
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Viewed:
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284 times
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In lugnet.off-topic.geek, David Koudys writes:
> Here's [my friend's] rationale, hopefully explained more fully (but I still
> think it's not quite kosher...)
>
> The time of the event--you grabbed 2 marbles
>
> there are 6 possible combinations in your hand
>
> r(1) r(2)
> r(1) b
> r(1) w
> r(2) b
> r(2) w
> b w
>
> those are the 6 unique possibilities in your hand at the time of the event
>
> One of those possibilities becomes invalidated because as soon as we see one
> of the marbles, we know it's red so the b w is gone...
>
> thus leaving only 5 possibilities, and what we want is the chance that both
> marbles are red, from the event--
>
> 1 in 5, = 20 percent.
>
> I understand it, but it still isn't sitting right with me.
Hmm... I just thought of something. Are there two separate questions at
work here?
Question 1: Having drawn two marbles from a bag of two red, one white, and
one blue marbles, what are the odds that the two you have drawn are both red?
Question 2: Having verified that one of the two marbles is red, what are
the odds that the second marble is also red?
Or is Q2 subordinate to Q1?
Darn it, I wish I'd paid more attention in statistics, lo these many years ago.
Dave!
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Message has 1 Reply:
 | | Re: math question (or pattern... whatever...)
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| (...) The original question: 4 marbles in a bag, 2 are red, one is white, one is blue You reach into the bag and grab 2 of them. You see that one of the marbles in your hand is red. What is the chance (either fraction or percent) that the other (...) (22 years ago, 3-Mar-03, to lugnet.off-topic.geek)
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Message is in Reply To:
| | Re: math question (or pattern... whatever...)
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| (...) Here's his rationale, hopefully explained more fully (but I still think it's not quite kosher...) The time of the event--you grabbed 2 marbles there are 6 possible combinations in your hand r(1) r(2) r(1) b r(1) w r(2) b r(2) w b w those are (...) (22 years ago, 3-Mar-03, to lugnet.off-topic.geek)
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