Introduction

Chapter 5

Basic Probability

Is a full house more likely to occur than a straight? Perhaps you are one of the many college students who play poker for fun (and maybe profit). Texas Hold ‘em is one of the most popular poker games on college campuses, and if you’ve played, you may have wondered about the probabilities of being dealt specific hands.

But beyond poker, questions regarding probability statements often influence our daily decision making. For instance, your local meteorologist reports that there is a 70% chance of rain today. Based on this information, should you ride your bike to campus or take the bus? The Federal Drug Administration reports that “the pill” is 98% effective in preventing pregnancy. How does this percentage affect your decision in choosing a specific type of birth control?

Each of these questions refers to the likelihood that random events will occur. Because much of our study of statistics has to do with analyzing data from random samples, it is important for us to understand what it means for an event to be random, and how we measure the likeliness that the event will occur.