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October 17th, 2013, 11:40 PM   #1
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Probability

Hi, i need help for the below qns. thanks.

Three unbiased dice are thrown .
Find the probability that

(i) they all show different numbers

ii). at least two shows the same number.
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October 18th, 2013, 02:04 AM   #2
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Re: Probability

(i) For the first die, how many values can you get?
For the second die, how many values can you get, given the value of the first die?
For the third die, how many values can you get, given the value of the first and second dice?

(ii)
How is this probability related to the probability found in question (i)?
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October 18th, 2013, 02:12 AM   #3
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Re: Probability

i). 6/6*5/6*4/6= 5/9

ii). 1- 5/9 = 4/9

Am i correct?
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October 18th, 2013, 04:56 AM   #4
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Re: Probability

Yes, that's correct.

You could also work out:

iii) The probability that all three are the same.

iv) The probability that two are the same and one is different.

That gives you a complete picture of all the possible outcomes.
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