When rolling a regular number cube (also known as a die), we know that it has six faces, each displaying a different number from 1 to 6. To find the probability that a 3 will not be rolled, we first need to consider all the possible outcomes and the outcomes that do not include the number 3.
The total number of outcomes when rolling the die is 6 (1, 2, 3, 4, 5, 6). Out of these outcomes, the numbers that do not include a 3 are 1, 2, 4, 5, and 6. Therefore, there are 5 outcomes where a 3 is not rolled.
To calculate the probability, we use the formula:
Probability = (Number of favorable outcomes) / (Total number of possible outcomes)
In this case, the number of favorable outcomes (not rolling a 3) is 5, and the total number of possible outcomes is 6. Plugging in these values, we get:
Probability = 5 / 6
So, the probability that a 3 will not be rolled when rolling a regular number cube is 5/6.