Question

Dan rolls 2 fair dice and adds the results from each.

Work out the probability of getting a total that is a factor of 15

Answer 1

`(1)/(6)`

Explanation:

The factors of 15 are numbers that can divide even through 15 without any remainders.

These numbers are 1, 3, 5 and 15;

When we roll two fair dice once, there are about 36 possible out comes and this is the sample space of rolling this fair dice.

1 2 3 4 5 6

1 (1, 1) (1, 2) (1, 3) (1, 4) (1, 5) (1, 6)

2 (2, 1) (2, 2) (2, 3) (2, 4) (2, 5) (2, 6)

3 (3, 1) (3, 2) (3, 3) (3, 4) (3, 5) (3, 6)

4 (4, 1) (4, 2) (4, 3) (4, 4) (4, 5) (4, 6)

5 (5, 1) (5, 2) (5, 3) (5, 4) (5, 5) (5, 6)

6 (6, 1) (6, 2) (6, 3) (6, 4) (6, 5) (6, 6)

The total that will give a factor of 15;

(1, 2) (2, 3) (1, 4) (2, 1) (3, 2) (4, 1)

Out of the 36 possible outcomes, we have 6 whose sum will give a factor of 15;

Probability of this =
`(6)/(36)` =
`(1)/(6)`