Probability of Choosing a Red or Green Marble

A bag contains 4 red marbles, 3 blue marbles, and 5 green marbles. If one marble is chosen at random from the bag, what is the probability that the marble is either red or green?

To find the probability of this event, you can use the formula:

$$ P(A) = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} $$