Refer to Exercise 55.

Assume you can eliminate one of the five choices, and you choose one of the remaining four at random as your answer.

a. What is the expected value of the number of points you get?

b. If you don’t answer a question, you get 0 points. The test makers advise you to guess if you can eliminate one or more answers. Do you think this is good advice?

Explain.

Exercise 55

A multiple-choice question has five choices. If you get the question right, you gain one point, and if you get it wrong, you lose 1∕4 point. Assume you have no idea what the right answer is, so you pick one of the choices at random.