If a fair six-sided die is rolled three times, what is the probability that the sum of the numbers rolled will be greater than or equal to 15?
To calculate this probability, we first need to determine the total number of possible outcomes when rolling a six-sided die three times. This can be calculated using the multiplication principle:

Total outcomes = 6^3 = 216

Next, we need to count the number of favorable outcomes where the sum of the numbers rolled is greater than or equal to 15. We can list these outcomes as follows:

(6, 6, 3), (6, 6, 4), (6, 6, 5), (6, 6, 6)
(6, 5, 4), (6, 5, 5), (6, 5, 6)
(6, 4, 5), (6, 4, 6)
(5, 6, 4), (5, 6, 5), (5, 6, 6)
(5, 5, 5), (5, 5, 6)
(4, 6, 5), (4, 6, 6)

There are a total of 16 favorable outcomes.

Now we can calculate the probability by dividing the number of favorable outcomes by the total number of possible outcomes:

Probability = Favorable outcomes / Total outcomes
            = 16 / 216
            ≈ 0.0741

So, the probability that the sum of the numbers rolled will be greater than or equal to 15 is approximately 0.0741 or 7.41%.