3. Chapter 7, Problems 6-7

In which of the following situations are you interested in a joint probability?

A. You really enjoy your town's Fourth of July fireworks display, but the town government has been considering cutting it out of the municipal budget this year, and the long-term weather forecast calls for a rainy summer. It would be really disappointing if the town went ahead with the show but it was rained out.

B. Justin has just seen his exam grade in economics. He has received a C and is worried that his overall grade will not allow him to pass the course.

C. Jane usually purchases season tickets to the local baseball team's games. Up until last year they were consistent winners, but then they had a losing season.

In which of the following situations are you interested in a conditional probability?

A. Money is tight this year, and you can really afford to send only one of your two sons, Richard and Brian, on a camping trip, but you feel that, to be fair, you have to offer the trip to both. Brian is the more athletic of the two, whereas Richard would just as soon have his adventures between the covers of a book.

B. Bailey is in the market for a new car and is considering whether to buy another minivan like the last two or something else. His daughter Jessie, who is soon to complete Driver Ed, thinks it would be cool to show up at parties driving a sports car.

C. It is nearly the end of the regular baseball season, and your favorite team is almost certain to make the playoffs. You have been invited to visit your friends in the country in late October. They are not baseball fans, but you do not want to miss the World Series if your team is in it. You need to answer them before the playoffs are over.

What would be a general statement related to that conditional probability?

A. Fathers who buy sports cars are more likely to let their daughters drive them than are fathers who buy minivans.

B. Both boys are more likely to accept the offer of the trip if you can afford to send only one than if you can afford both.

C. Once in the playoffs, your team is more likely to make it to the World Series than not to.