Maths Probability

Question

What is the probability of getting a 10 or a 11 when a pair of dice are rolled?

How to do

Answer 1

Try it out. Count how many combinations lead to the expected result and divide through 36.

Answer 2

There are 36 possible rolls (6*6).

On the first dice, a 4, 5 or 6 will give you a roll that can provide a valid solution.

So, here is a list of rolls that are valid:

    D1    D2    Result
    ------------------
    4     6     10
    5     6     11
    5     5     10
    6     4     10
    6     5     11

Total of 5 solutions from 36.

(5/36)*100 = 13.9%

or

5/36 = 10/72 and 10/72 = 1/7.2

If you were a betting man, you would offer someone 1:6 they can't throw this number, or 1:8 that you can throw the number :)

Answer 3

With die one across the top and die 2 down the left you can see that there is a possible 5 out of 36 (which is 6 x 6) chance.

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

The probability of a particular combination is 1 in 36 Because 5 combinations add to 10 or 11 it makes it 5/36 or 0.139.