You roll two dice. What is the probability of getting a 3 or a 6 on the second die, given that you rolled a 1 on the first die?

1 Answer
Apr 9, 2018

P(3 or 6) =1/3P(3or6)=13

Explanation:

Notice that the outcome of the first die does not affect the outcome of the second. We are only asked about the probability of a 3or 63or6 on the second die.

There are 6363 numbers on a die, of which we want two - either 3 or 63or6

P(3 or 6) = 2/6 = 1/3P(3or6)=26=13

If you are wanting the probability for both dice, then we have to consider the probability of getting the 11 first.

P(1,3) or (1,6) = P(1,3) +P(1,6)P(1,3)or(1,6)=P(1,3)+P(1,6)

= (1/6 xx 1/6) + (1/6 xx 1/6)=(16×16)+(16×16)

=1/36 +1/36 = 2/36 = 1/18=136+136=236=118

We could also have done: 1/6 xx 1/3 = 1/1816×13=118