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July 12th, 2012, 09:46 PM   #1
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The probability that: two are white and one is blue.

A box contains identical balls of which 12 are red, 16 white and 8 blue. Three balls are drawn from the box one after the other without replacement. Find the probability that: two are white and one is blue.
Please I need working and explaination.
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July 12th, 2012, 10:04 PM   #2
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Re: The probability that: two are white and one is blue.

In the numerator, we will have the product and in the denominator . There are 3 distinct ways to order the balls, hence:

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July 13th, 2012, 02:17 AM   #3
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Re: The probability that: two are white and one is blue.

Yes you are right. That is the answer. Just give me a clue on how you know the number of orders, for example, this one is in this order P(wwb) + P(bww) + P(wbw) i.e 3 orders.
How do you know the one that should be in two, three or six orders?
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July 13th, 2012, 09:06 AM   #4
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Re: The probability that: two are white and one is blue.

The way I looked at it, there are three positions the one blue ball may occupy.
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July 13th, 2012, 10:42 AM   #5
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Re: The probability that: two are white and one is blue.

Alright! Thank you for the help.
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July 13th, 2012, 01:53 PM   #6
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Re: The probability that: two are white and one is blue.

Hello, Chikis!

Another approach . . .


Quote:
A box contains identical balls of which 12 are red, 16 white and 8 blue.
Three balls are drawn from the box one after the other without replacement.
Find the probability that: two are white and one is blue.







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July 25th, 2012, 03:41 AM   #7
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Re: The probability that: two are white and one is blue.

A box contains identical balls of which 12 are red, 16 white and 8 blue. Three balls are drawn from the box one after the other without replacement. Find the probability that: two are white and one is blue.


possible combination WWB + WBW + BWW
= 16/36 * 15/35 * 8/34 + 16/36 * 8/35 * 15/34 + 8/36 * 16/35 * 15/34
= 16/119
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July 25th, 2012, 07:45 PM   #8
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Re: The probability that: two are white and one is blue.

Ahhh....I see...you're doing this to SNEAK IN your advertizing
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July 25th, 2012, 07:52 PM   #9
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Re: The probability that: two are white and one is blue.

Quote:
Originally Posted by M4mathematics
A box...
I agree, you have posted the link to your site more than enough times on our forums.

It's great that you want to help, but please do so without spamming each post with a link. Thank you for your cooperation.
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July 25th, 2012, 08:32 PM   #10
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Re: The probability that: two are white and one is blue.

thanks, i remember next time.........
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