test question

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  #1  
Old 09-20-10, 08:12 PM
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test question

can someone help with this question
In a jar there are 5 red marbles
2 blue
4 yellow
4 green
If you do 2 random drawings from jar picking 1 marble each time what is the probablity you will draw 2 of the same color.
thanks for your help
 
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Old 09-21-10, 09:32 AM
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Does your teacher know you are cheating on your homework?
 
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Old 09-21-10, 09:40 AM
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Is this a test for us or are you asking us for help with a question you've been asked to solve on a test?
 
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Old 09-21-10, 12:58 PM
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Oh, before doing the math you need to know if the marble from the first drawing is returned to the jar before the second drawing or if a marble once drawn is not returned to the jar. That will affect the odds.
 
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Old 09-21-10, 04:45 PM
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33% of the total are red

13% are blue

27% are yellow

27% are green

That's a start, that might help. These kinds of questions are found on I.Q.tests.

I'll say 1 in 16, based on the odds that if you are unlucky and first draw the 1 in 8 odds blue, that to get another blue would again be 1 in 8. Then again I might be way off and the answer is 1 in 237 million.

Oops, I forgot on the second drawing there will be one less blue and now the odd are 1 in 14. Hmmm. 1 in 22 odds?
 

Last edited by ecman51; 09-21-10 at 05:17 PM.
  #6  
Old 09-21-10, 05:18 PM
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Originally Posted by Pilot Dane View Post
Oh, before doing the math you need to know if the marble from the first drawing is returned to the jar before the second drawing or if a marble once drawn is not returned to the jar. That will affect the odds.
I have a feeling you do not return it to the jar.
 
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