4.1 Intro to Random Variables

Choose the correct examples of discrete variable.

• A film critic's rating of a film (0 - 4 stars)

• Time taken to commute to work

• The sum of the numbers rolled on a pair of dice

• Winning ticket number drawn from a raffle

• Amount of gasoline a car

Classify.

The numbers of cheeseburgers a fast-food restaurant serves each day

• None of these

• Abstract

• Continuous

• Discrete

Discrete or Continuous?

Let x represent the number of books in a university library.

• Discrete

• Continuous

Discrete or Continuous?

Let x represent the volume of blood drawn for a blood test.

• Discrete

• Continuous

Discrete or Continuous?

Let x represent the length of time it takes to get to work.

• Discrete

• Continuous

Discrete or Continuous?

Let x represent the number of tornadoes in the month of June in Oklahoma.

• Discrete

• Continuous

Is the following a probability distribution?

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.

• No, all probabilities are not be between 0 and 1 inclusive

• No, the sum of all the probabilities is not 1.

• Yes, because the distribution is symmetric

Is the following a probability distribution?

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.

• No, all probabilities are not be between 0 and 1 inclusive

• No, the sum of all the probabilities is not 1.

• Yes, because the distribution is symmetric

Is the following a probability distribution?

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.

• No, all probabilities are not be between 0 and 1 inclusive

• No, the sum of all the probabilities is not 1.

• Yes, because the distribution is symmetric

A marketing survey compiled data on the number of cars in households. If X = the number of cars in a randomly selected household, and we omit the rare cases of more than 5 cars, then X has the probability distribution shown. What is the probability that a randomly chosen household has at least two cars?

• 0.20

• 0.29

• 0.39

• 0.61