Chapter 4.5, Problem 1AC

Applying the Concepts 4–5

Counting Rules and Probability

One of the biggest problems for students when doing probability problems is to decide which formula or formulas to use. Another problem is to decide whether two events are independent or dependent. Use the following problem to help develop a better understanding of these concepts.

Assume you are given a five-question multiple-choice quiz. Each question has 5 possible answers: A, B, C, D, and E.

1. How many events are there?

2. Are the events independent or dependent?

3. If you guess at each question, what is the probability that you get all of them correct?

4. What is the probability that a person guesses answer A for each question?

Assume that you are given a five-question matching test in which you are to match the correct answers in the right column with the questions in the left column. You can use each answer only once.

5. How many events are there?

6. Are the events independent or dependent?

7. What is the probability of getting them all correct if you are guessing?

8. What is the difference between the two problems?