A bag contains 7 red marbles, 5 yellow marbles, 6 blue marbles, 4 green marbles, and 3 orange marbles. What is the probability of randomly selecting a yellow marble out of the bag?
Add all the numbers up, you get 25. There is 5 yellow marbles, so that's a 5/25 chance of picking a yellow one, now you just have to simplify, you then get 1/5, because 5 ÷ 5 is 1, and 25 ÷ 5 is 5.