Suppose each box of a popular brand of cereal contains a pen as a prize. The pens come in four colors: blue, red, green, and yellow. Each color of pen is equally likely to appear in any box of cereal. Reflect on all the devices we've used to simulate an experiment: fair coin, dice, spinners, bags of marbles, etc).

What device would you use to simulate the probability of drawing a blue pen from a cereal box? You must explain why you would choose this device.