I created this simulation to explore a probability problem posed by my friend Ken. The problem involves a bag with four different types of miniature Hershey bars (with 15 of each). The question is how many bars do you need to choose (randomly) to have a 50% probability of getting at least one of each type of candy bar. Use the slider to control how many candy bars to select. When you click the Green Flag, the project will then run 1 million trials, and you can see the probability of getting at least one of each type of candy bar. (Want to make the simulation run a little faster? Hide the list monitors by clicking the "run faster" button.)