SOLUTION: A fair pair of dice is rolled and the sum of the points is noted. What is the probability that one of the dice results in a point of 6, given that the sum of the points is 8?
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Question 1137021: A fair pair of dice is rolled and the sum of the points is noted. What is the probability that one of the dice results in a point of 6, given that the sum of the points is 8? Answer by greenestamps(13200) (Show Source):
The sample space for the problem is all the outcomes where the sum of the two dice is 8; the "good" outcomes are the ones that have a 6 on one of the two dice.
6+2
5+3
4+4
3+5
2+6
There are 5 ways to get a sum of 8; 2 of those ways have 6 on one of the two dice.
The probability that one of the dice shows 6, given that the sum of the two dice is 8, is 2/5.
Using the formal mathematical definition of conditional probability....
P(one of the dice is 6 | the sum of the two dice is 8)
= P((one of the dice is 6) AND (the sum of the dice is 8)) 2/36 2
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P(sum of the dice is 8) 5/36 5