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 21:08:51 GMT
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Viewed:
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249 times
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In lugnet.off-topic.geek, David Koudys writes:
> k, here's something that came across my desk...
>
> you have a bag with 4 marbles in it.
>
> 2 of the marbles are red
> 1 marble is white
> 1 marble is blue
>
> you reach in and grab 2 random marbles
>
> you open up your hand a bit to only see the colour of one of those 2
> marbles, and it happens to be red
>
> what is the chance that the other marble in your hand is also red?
>
> I say it's 33 percent
> my friend says it's 20 percent
<long snip>
you're right, in both senses. Your logic for the first solution is valid,
and your identification of his error in the second solution (which would
lead to the same answer) is also correct. It is, indeed, 33%
Adrian
--
http://www.brickfrenzy.com
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Message has 2 Replies:
 | | 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)
| | | Re: math question (or pattern... whatever...)
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| (...) My knowledge of stats gives me less than 1 in one zillion chance of answering any random stats question correctly, but I likewise agree: The essential question is "If you reach into a bag with a red, a white, and a blue marble, then what are (...) (22 years ago, 3-Mar-03, to lugnet.off-topic.geek)
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Message is in Reply To:
| | math question (or pattern... whatever...)
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| k, here's something that came across my desk... you have a bag with 4 marbles in it. 2 of the marbles are red 1 marble is white 1 marble is blue you reach in and grab 2 random marbles you open up your hand a bit to only see the colour of one of (...) (22 years ago, 3-Mar-03, to lugnet.off-topic.geek)
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