Two standard numbers cubes are thrown. Given that one of the cubes shows a two, what is the probability that the sum of the numbers that come up on the two cubes is four?

The other one has to be two does it not?

then 1/6

To find the probability that the sum of the numbers is four, given that one of the cubes shows a two, we need to determine the number of outcomes where the sum is four when one of the cubes shows a two.

First, let's list all the possible outcomes when one of the cubes shows a two:
(2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6)

Out of these six outcomes, only one of them results in a sum of four: (2, 2)

Therefore, the probability that the sum of the numbers is four, given that one of the cubes shows a two, is 1 out of 6.

So, the answer is:

Probability = Number of favorable outcomes / Number of possible outcomes
= 1 / 6
= 1/6

Hence, the probability is 1/6.