A pair of dice are rolled and the sum on their upturned faces is recorded. What is the probability that the sum showing is 8, given the one die is showing a 5?

That means the second die is 3.

PR(3)=1/6

To find the probability that the sum showing is 8, given that one die is showing a 5, we can use conditional probability.

First, let's determine the total number of possible outcomes. When two dice are rolled, there are a total of 6 possible outcomes for each die, resulting in a total of 6 x 6 = 36 possible outcomes.

Now, let's consider the condition that one die is showing a 5. There are a total of 6 possibilities for the other die: 1, 2, 3, 4, 5, or 6.

Out of these 6 possibilities, we need to find the number of outcomes where the sum is 8. We can do this by listing all the pairs that satisfy this condition: (3, 5), (4, 4), (5, 3).

So, there are 3 outcomes where the sum is 8 and one die is showing a 5.

Therefore, the probability that the sum showing is 8, given that one die is showing a 5, is 3/6, which simplifies to 1/2.

Thus, the probability is 1/2 or 50%.