Name______________________________
K. Hartford Chapter 4 Practice (Probability)
Answer the question. 1. Which of the following cannot be a probability?
A. 0
B. 1
C. - 1
2. Which of the following following cannot be a probability? 3 2 A. B. 5 3
C.
5 3
D.
1 2
D.
1 2
SHORT ANSWER. Write the word or phrase that best completes completes each statement or answers the question.
3. What is the probability probability of an impossible impossible event? 4. On a multiple choice test with four possible answers for each question, what is the probability of answering a
question correctly if you make a random guess? Find the indicated probability. 5. On a multiple choice test, each question has 5 possible answers. If you make a random guess on the first question, what is the probability that you are correct?
6. Two 6-sided dice are rolled. What is the probability probability that the sum of the two numbers numbers on the dice will be 4? 7. Two 6- sided dice are rolled. What is the probability that the sum of the two numbers on the dice will be 3? 8. In a poll, respondents were asked whether they they had ever been in a car accident. 138 respondents indicated that they they had been in a car accident and 494 respondents said that they had not been in a car accident. If one of these respondents is randomly selected, what is the probability of getting getting someone who has been in a car accident? Round to the nearest thousandth, if necessary.
Answer the question, considering an event to be "unusual" if its probability is less than or equal to 0.05 9. Assume that a study of 500 randomly selected school bus routes showed that 477 arrived on time. Is it "unusual" for a school bus to arrive late?
eight of clubs? 10. If you drew one card from a standard deck, would it be "unusual" to draw an eight From the information provided, create the sample space of possible outcomes. 11. Both Fred and Ed have a bag of candy containing a lemon drop, a cherry drop, and a lollipop. Each takes out piece and eats it. Draw a tree diagram to represent the sample space. What are the possible pairs of candies eaten? Answer the question. 12. HONORS CLASS ONLY: Find the odds against correctly guessing the answer to a multiple choice question wit
6 possible answers. 13. IHONORS CLASS ONLY:: In a certain town, 25% of people commute to work by bicycle. If a person is selected
randomly from the town, what are the odds against selecting someone who commutes by bicycle?
1
Find the indicated complement. 1 14. If P(A) = , find P(A). 7
15. If a person is randomly selected, find the probability that his or her birthday is not in May. Ignore leap years. Find the indicated probability. 16. A spinner has equal regions numbered 1 through 21. What is the probability that the spinner will stop on an even number or multiple of 3?
17. If you pick a card at random from a well shuffled deck, what is the probability that you get a face card or a spade? 18. The table below describes the smoking habits of a group of asthma sufferers. Occasional Regular Heavy Nonsmoker smoker smoker smoker Total Men 433 50 66 34 583 Women 408 31 70 35 544 Total 841 81 136 69 1127 If one of the 1127 people is randomly selected, find the probability that the person is a man or a heavy smoker. 19. A sample of 100 wood and 100 graphite tennis rackets are taken from the warehouse. If 6 wood and 14 graphite are defective and one racket is randomly selected from the sample, find the probability that the racket is wood or defective. (hint: make a table) 20. A study of consumer smoking habits includes 183 people in the 18-22 age bracket (59 of whom smoke), 140 people in the 23-30 age bracket (34 of whom smoke), and 99 people in the 31-40 age bracket (22 of whom smoke). If one person is randomly selected from this sample, find the probability of getting someone who is age 18-22 or does not smoke. 21. The manager of a bank recorded the amount of time each customer spent waiting in line during peak business hours one Monday. The frequency table below summarizes the results. Waiting Time Number of (minutes) Customers 0-3 11 4-7 9 8-11 11 12-15 5 16-19 5 20-23 1 24-27 3 If we randomly select one of the customers represented in the table, what is the probability that the waiting time is at least 12 minutes or between 8 and 15 minutes? 22. A card is drawn from a well-shuffled deck of 52 cards. Find P(drawing an ace or a 9). 23. The table below describes the smoking habits of a group of asthma sufferers. Occasional Regular Heavy Nonsmoker smoker smoker smoker Total Men 444 37 76 34 591 Women 429 47 86 44 606 Total 873 84 162 78 1197 If one of the 1197 people is randomly selected, find the probability of getting a regular or heavy smoker. 24. In one town, 39% of all voters are Democrats. If two voters are randomly selected for a survey, find the probability that they are both Democrats. Round to the nearest thousandth if necessary.
2
25. Find the probability of correctly answering the first 5 questions on a multiple choice test if random guesses are made and each question has 6 possible answers. 26. When a pair of dice are rolled there are 36 different possible outcomes: 1-1, 1-2, ... 6-6. If a pair of dice are rolled 4 times, what is the probability of getting a sum of 5 every time? (3 sig figs) 27. A study conducted at a certain college shows that 51% of the school's graduates find a job in their chosen field within a year after graduation. Find the probability that 5 randomly selected graduates all find jobs in their chosen field within a year of graduating. Round to the nearest thousandth if necessary. 28. You are dealt two cards successively (without replacement) from a shuffled deck of 52 playing cards. Find the probability that both cards are black. Express your answer as a simplified fraction. 29. You are dealt two cards successively (without replacement) from a shuffled deck of 52 playing cards. Find the probability that the first card is a King and the second card is a queen. Express your answer as a simplified fraction. 30. What is the probability that 4 randomly selected people all have different birthdays? Round to four decimal places. 31. A IRS auditor randomly selects 3 tax returns from 45 returns of which 15 contain errors. What is the probability that she selects none of those containing errors? Round to four decimal places. 32. Among the contestants in a competition are 49 women and 20 men. If 5 winners are randomly selected, what is
the probability that they are all men? Round to five decimal places. 33. A sample of 4 different calculators is randomly selected from a group containing 46 that are defective and 26 that have no defects. What is the probability that all four of the calculators selected are defective? Round to four decimal places.
3
Answer Key Testname: CH4 1. C 2. C 3. 0 1 4. 4 5. 1
5 6. 1 12
7.
1 18
8. 0.218 9. Yes 10. Yes 11. LD- LD CD- LD LP- LP LD- CD CD- CD LD- LP LP-CD CD-LP LP- LD 12. 5 : 1 13. 3 : 1 14. 6
7 15. 334 365 16. 2 3 17. 11 26 18. 0.548 19. 0.57 20. 0.867 21. 0.556 22. 2 13 23. 0.201 24. 0.152 25. 1 7776 26. 0.000152 27. 0.035 28. 25 102 29. 4 663 30. 0.9836 31. 0.2861
32. 0.00138 33. 0.1586
4
