Question

What is the probability of rolling a sum of 3

on a standard pair of six-sided dice? Express your answer as a fraction or a decimal number rounded to three decimal places, if necessary.

Answer 1

1/18

Explanation:

To roll a sum of 3, you must roll a 1 followed by a 2, or a 2 followed by a 1.

P(1 then 2) = 1/6 × 1/6 = 1/36

P(2 then 1) = 1/6 × 1/6 = 1/36

The total probability is therefore:

P(sum of 3) = 1/36 + 1/36 = 1/18