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Probability question

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Probability question

by vinni.k » Thu Apr 28, 2011 10:52 am
Hi,

Please help me in solving the following question with a short method. My method was very long and time consuming.

What is the probability that the sum of two dice will yield a 10 or lower ?

My method :- There are three combination of 2 dice that yield a sum of 10: (5 + 5), (6 + 4), (4 + 6)
and there are 30 combination of 2 dice that yield a sum lower than 10:(1 + 1), (1 + 2), (2 + 1)..etc.

Actually i wrote all the 30 combinations, which is time consuming; now, 3/36 + 30/36 = 33/36, which is equal to 11/12(Answer)

Thanks
Vinni
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by vineeshp » Thu Apr 28, 2011 11:28 am
How about finding the probability of finding 11 and 12. And then subtracting it from 1.

That's the shortest method.
Vineesh,
Just telling you what I know and think. I am not the expert. :)
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by Tani » Thu Apr 28, 2011 3:54 pm
You still need the total number of combinations. That can be done quickly without spelling them out.

There are 6 possible results from the first dice. For each of those there are 6 possible results from the second. That means 36 total.

Now, figure the cases that will give you more than ten: 5,5; 5,6; and 6,6. subtract those three from 36 and you get 33. The probability of 10 or lower is 33/36.
Tani Wolff
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