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April 22, 2026, 09:20:25 am
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Author Topic: a bag contains....  (Read 644 times)  Share 

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scatteam_2

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a bag contains....
« on: September 30, 2010, 04:54:39 am »
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3 red, 4 white and 5 black balls. if 3 balls are taken out without replacement, what is the probability that they are all the same colour?

Could someone please help me step by step?
Thank you!
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8039

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Re: a bag contains....
« Reply #1 on: September 30, 2010, 05:34:44 am »
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How I understand it we want RRR or BBB or WWW (since 3 taken out). For red we have 3 out of a total of 12 balls so we start with a probability of 3/12 of getting a red. Multiply that by 2/11 (since we have permanently removed a red ball we have less red balls and total balls) then do that a third time which makes 3/12 times 2/11 times 1/10 = 1/220. Do the same for the other balls and add up all the values.
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