Probability tells us the chance or likelihood that a particular event will occur. Whether or not we realize it, every day we use probability to make decisions. For instance, when deciding whether to take an umbrella, we check the weather forecast to see the probability that it will rain. In this instance, probability tells us the likelihood that it will rain; however, the decision about taking an umbrella is based on an individual’s willingness to risk getting rained on. Some people will take an umbrella, when the probability of rain is at least 40%, while others will wait until the probability is at least 60%.