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Old 07-29-2007   #3
Kiwi Maths Teacher
Posts: n/a

If you throw two dice together then the probabilities of interest are theseP(1)=0P(2)=1/36P(3)=2/36P(4)=3/36P(5)=4/36The answer to your question is[P(3)+P(5)]/[P(2)+P(3)+P(4)+P(5)]=[6/36]/[10/36]=3/5 or 0.6Here is the reasoningThe only outcomes of interest are if the total is 3 or 5hence the numeratorGiven that the sum is 5 or less then the denominator is the sum of the probabilities that the total is 2 or 3 or 4 or 5.Hope this helps.