Chapter 4
The Binomial Distribution
IN THIS CHAPTER
Identifying a binomial random variable
Finding probabilities using a formula or table
Calculating the mean and variance
A random variable is a characteristic, measurement, or count that changes randomly according to some set of probabilities; its notation is X, Y, Z, and so on. A list of all possible values of a random variable, along with their probabilities, is called a probability distribution. One of the most well-known probability distributions is the binomial. Binomial means “two names” and is associated with situations involving two outcomes: success or failure (hitting a red light or not; developing a side effect or not). This chapter focuses on the binomial distribution — when you can use it, finding probabilities for it, and finding the expected value and variance.
Characteristics of a Binomial
A random variable has a binomial distribution if all the following conditions are met:
- There are a fixed number of trials (n).
- Each trial has two possible outcomes: success or failure.
- The probability of success (call it p) is the same for each trial.
- The trials are independent, meaning the outcome of one trial doesn’t influence ...