If a box contains 3 red, 4 blue, and 5 green balls, what is the probability of selecting a green ball?

To determine the probability of selecting a green ball from the box, we first need to identify the total number of balls present. The box contains 3 red, 4 blue, and 5 green balls. By adding these quantities together, we find the total number of balls:

3 (red) + 4 (blue) + 5 (green) = 12 balls in total.

Next, we focus on the specific event of selecting a green ball. There are 5 green balls in the box. The probability of an event is calculated using the formula:

Probability of an event = (Number of favorable outcomes) / (Total number of possible outcomes).

Applying this formula here, the number of favorable outcomes (selecting a green ball) is 5, and the total number of possible outcomes (the total number of balls) is 12. Thus, the probability of selecting a green ball is:

5 (green balls) / 12 (total balls) = 5/12.

This means that the correct answer is indeed 5/12, representing a little less than half of the total outcomes, which reflects the proportion of green balls in the overall collection of colored balls.