Abag contains 3 marbles and 6 blue marbles. what is the probability of randomly selecting a red marble from the bag?

Ll you need to do here is just find the ratio of red marbles to all of the marbles.                    2 red                       2 red + 3 blue + 5 yellow + 2 green
when you add everything up, you get 2/12, which is equal to 1/6.