# Probability with dice

• Jun 7th 2009, 11:59 PM
Murphie
Probability with dice
Two dice are rolled. Find the probability of rolling a sum greater than 6.
Confused on how to work this but...
Wouldn't the probability be just .71?
Possible outcomes and probabilitiy

2 1/36
3 2/36
4 3/36
5 4/36
6 5/36
7 6/36
8 5/36
9 4/36
10 3/36
11 2/36
12 1/36

so you would add the probability of all the possible outcomes greater than 6 which is 21 and divide that by the remaining possibilities? 15/21 = .71? or 71%?
• Jun 8th 2009, 12:20 AM
Prove It
Quote:

Originally Posted by Murphie
Two dice are rolled. Find the probability of rolling a sum greater than 6.
Confused on how to work this but...
Wouldn't the probability be just .71?
Possible outcomes and probabilitiy

2 1/36
3 2/36
4 3/36
5 4/36
6 5/36
7 6/36
8 5/36
9 4/36
10 3/36
11 2/36
12 1/36

so you would add the probability of all the possible outcomes greater than 6 which is 21 and divide that by the remaining possibilities? 15/21 = .71? or 71%?

How many of the 36 possibilities have a sum greater than 6?

21.

So $Pr\left(\sum > 6\right) = \frac{21}{36} = \frac{7}{12}$.
• Jun 8th 2009, 12:52 AM
mr fantastic
Quote:

Originally Posted by Murphie
Two dice are rolled. Find the probability of rolling a sum greater than 6.
Confused on how to work this but...
Wouldn't the probability be just .71?
Possible outcomes and probabilitiy

2 1/36
3 2/36
4 3/36
5 4/36
6 5/36
7 6/36
8 5/36
9 4/36
10 3/36
11 2/36
12 1/36

so you would add the probability of all the possible outcomes greater than 6 which is 21 and divide that by the remaining possibilities? 15/21 = .71? or 71%?

Use this chart to count the favourable outcomes.