Question

You roll two dice, what is the probability of getting a sum of 5, given the first die is a three?

Answer 1

The question reduces to finding the probability of rolling a 2 on a die.

Answer 2

So that would be 2/36 where there are 36 possibilities?

Answer 3

This should help

Answer 4

Not really. It is given that the first die is a three. The number rolled on the first die has no effect on the number rolled on the second die. To make a sum of 5, we need a 2 on the second die. The probability of rolling a 1, 2, 3, 4, 5 or 6 is 1/6.

Answer 5

Ahh! Thank you both, the graph made sense and kropot72 cleared it up. So, it is 1/6.

Answer 6

It's actually (1/6)^2

Answer 7

The 2 represents the two dice?

Answer 8

Yes, 1/6 is correct.
(1/6)^2 ignores that it is given that the first die is a 3. (1/6)^2 is the probability of rolling a 3 on the first die and a 2 on the second die.

Answer 9

Ah, my mistake.

Answer 10

np :)

Answer 11

I understood that 5/36 reduces down to 1/6. Thank you both very much!

Answer 12

Note that (1/6)^2 stands for
\[(\frac{1}{6})^{2}=\frac{1}{6}\times\frac{1}{6}=\frac{1}{36}\]
and is not the correct answer.

Answer 13

Yes, 1/6 and not 1/6^2.

Answer 14

Correct :)