MATH200 — Practice Quiz: Chapter 5 — 50 min  

Practice Quiz: Chapter 5

Work this like a regular quiz, using only your crib sheet. Give yourself a maximum of 50 minutes, then turn to the solutions and see how you did.

LOOK! Remember, you must show your work for full credit on any problems involving computation.

Note:  Many students have a lot of trouble with probability, so this quiz is extra long to help you practice. The total here is more than the regular number of points, but the real quiz will be shorter and will count the regular number of points.

One or two problems can’t be solved using the techniques we learned in class. In those cases, give the reason they can’t be solved, in a very few words.

1(points: 2)  A seed packet is labeled “probability of germination guaranteed 95%”. Give two interpretations of this probability.

 

2(points: 3) You toss three coins.
(a) Construct the sample space of equally likely events.
(b) Find P(2H), the probability of getting exactly two heads.

 

3(points: 3)  P(A), the probability of event A, is 0.7. A and B are complementary events.
(a) Find P(not A).
(b) Find P(B).
(c) Find P(A and B).
If any of the above cannot be determined from the information given, say so.

 

4(points: 2) You draw a card at random from the deck. What’s the probability that it’s an ace or a spade?

 

5(points: 2)  In Monopoly, if you roll doubles you get an extra roll, but if you roll doubles three times in a row you go to jail.
(a) On any given turn, what’s the probability you’ll roll doubles? (The picture on page 228 may help.)
(b) On any given turn, what’s the probability you’ll go to jail for rolling doubles three times in a row?
6(points: 2) Students attending a job fair included 62 nursing majors, 45 business majors, 12 hospitality, 8 construction, 10 science, and 63 liberal arts. If you randomly select a student, what’s the probability that he or she is majoring in nursing or liberal arts?

 

7(points: 4) You’ll be missing your favorite show while you’re in Statistics class. You set your Tivo, but just to be safe you also set your creaky old VCR to record it. But you’re having roommate trouble, and there’s a 20% chance your roommate will reprogram the Tivo. The VCR just unaccountably fails 30% of the time. What’s the probability that your program will be recorded? (Hint: What is your friend when a probability problem looks complex?)

 

8(points: 4) Tom Turkey invested in two stocks, A and W. There is a 0.90 probability that company A will go bankrupt, and a 0.80 probability that company W will go bankrupt. Assuming the two companies have no connection, find the probabilities that (a) both will go bankrupt; (b) one of them, but not both, will go bankrupt; (c) neither will go bankrupt.

 

9(points: 2)  A poll found that 45% of baseball fans had attended a game in person within the past year. Of five randomly selected baseball fans, find the probability that at least one had not attended a game within the past year.

 

10(points: 2) A second poll found that 86% of baseball fans favored drug testing for baseball players. What’s the probability that a given baseball fan had attended a game within the past year and favored drug testing?

 

11(points: 3) In 2003 a federal government survey estimated that 58.2% of US households had both a cell phone and a landline, 2.8% had only cell service, and 1.6% had no phone service at all.
(a) Construct a probability model for type of phone service to US households.
(b) Polling agencies try (in theory) not to call cell phones, because consumers object to paying for the calls. What proportion of US households could be reached by a landline in 2003?

 

Solutions to this practice quiz are available at http://www.tc3.edu/instruct/sbrown/stat/