Counting Successes: A General Simulation Model

A basketball player goes to the free-throw line 10 times in a game and makes all 10 shots. A student guesses all the answers on a 20-question true—false test and gets 18 of them wrong. Twelve persons are selected for a jury, and 10 of the 12 are female. Unusual? Some would say that the chances of these events happening are very small. But, as we have seen, calculating the probabilities to evaluate the chances of these events requires some careful thought about a model. The three scenarios outlined above all have certain common traits. They all involve the repetition of the same event over and over. They all have as a goal counting the number of “successes” in a fixed number of repetitions. This activity discusses how to construct a simulation model for events of this type so that we can approximate their probabilities and decide for ourselves whether or not the events are unusual.