Let's say we have a box with 6 marbles: 3 red, 1 blue, 1 green, and 1 yellow. What is the probability of picking a yellow marble, keep it, and then
picking a blue marble?
Explanation: First you find the probability of picking a yellow marble, 1/6. Then you multiply the probability of picking a blue marble, 1/5 since there are now only five marbles total. Then multiply those to see what the final probability is, 1/6*1/5=1/30.