I can't remember

06-01-2008, 03:43 PM

Two standard dice are rolled. What is the probability of the sum on the two dice being less than 10?

I thought since there are 6 ways each dice could potentially end up, that I should multiply them to get 36 possible outcomes. Then I said well it would be easier to find the probability of rolling a 10 or higher. so I wrote out all the possabilities of combinations of 10 or higher.

4,6

6,4

5,5

5,5

5,6

6,5

6,6

6,6

That totals 8 combination out of 36 that could be ten or higher, so 8/36= 2/9. since I wanted less than ten 1-(2/9) = 7/9 probability of getting less than 10.

my question is did I do this right, and if so, was there an easier way?

I thought since there are 6 ways each dice could potentially end up, that I should multiply them to get 36 possible outcomes. Then I said well it would be easier to find the probability of rolling a 10 or higher. so I wrote out all the possabilities of combinations of 10 or higher.

4,6

6,4

5,5

5,5

5,6

6,5

6,6

6,6

That totals 8 combination out of 36 that could be ten or higher, so 8/36= 2/9. since I wanted less than ten 1-(2/9) = 7/9 probability of getting less than 10.

my question is did I do this right, and if so, was there an easier way?