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July 12th, 2012, 09:46 PM  #1 
Senior Member Joined: Jan 2012 Posts: 736 Thanks: 7  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. 
July 12th, 2012, 10:04 PM  #2 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs  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: 
July 13th, 2012, 02:17 AM  #3 
Senior Member Joined: Jan 2012 Posts: 736 Thanks: 7  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? 
July 13th, 2012, 09:06 AM  #4 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs  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.

July 13th, 2012, 10:42 AM  #5 
Senior Member Joined: Jan 2012 Posts: 736 Thanks: 7  Re: The probability that: two are white and one is blue.
Alright! Thank you for the help.

July 13th, 2012, 01:53 PM  #6  
Math Team Joined: Dec 2006 From: Lexington, MA Posts: 3,267 Thanks: 408  Re: The probability that: two are white and one is blue. Hello, Chikis! Another approach . . . Quote:
 
July 25th, 2012, 03:41 AM  #7 
Newbie Joined: Jul 2012 From: India Posts: 8 Thanks: 0  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 
July 25th, 2012, 07:45 PM  #8 
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,279 Thanks: 1023  Re: The probability that: two are white and one is blue.
Ahhh....I see...you're doing this to SNEAK IN your advertizing 
July 25th, 2012, 07:52 PM  #9  
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs  Re: The probability that: two are white and one is blue. Quote:
It's great that you want to help, but please do so without spamming each post with a link. Thank you for your cooperation.  
July 25th, 2012, 08:32 PM  #10 
Newbie Joined: Jul 2012 From: India Posts: 8 Thanks: 0  Re: The probability that: two are white and one is blue. thanks, i remember next time......... 

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