Review Questions on Ch4 and Ch5 1. Find the mean of the distribution shown. x 1 2 P(x) 0.40 0.60 A) 1.60 B) 0.87 C) 1.33 D) 1.09 2. A married couple has three children, find the probability they are all boys or all girls A) 3/8 B) 1/2 C) 1/8 D) 1/4 3. A store manager wants to display 5 different brands of toothpaste in a row. How many ways can this be done? A) 24 B) 5 C) 120 D) 20 4. What type of probability uses the relative frequency? A) Classical probability C) Subjective probability B) Empirical probability D) Conditional probability 5. What is the subset of the sample space of a probability experiment? A) outcome B) event C) sample space D) Venn diagrams 6. In a certain population of hospital patients the probability that a randomly selected patient will have heart disease is 0.20 and the probability that a patient with heart disease is a smoker is 0.80. What is the probability that a randomly selected patient from this population will be a smoker and have heart disease? A) 0.30 B) 0.16 C) 0.80 D) 0.20 7. The probability that a new drug will be successful is 90% is an example of a(n) probability A) classical B) empirical C) subjective D) percentage 8. If the probability that it will rain tomorrow is 30% then the probability that it won t rain tomorrow is... A) 7% B) 3% C) 70% D) 30% 9. Which of the following events is mutually exclusive when rolling a die? A) get an odd number and a number < 2 C) get an even number and an odd number B) get a prime number and an odd number D) get a prime number and an even number 10. The probability that a student has a computer is 0.91 and the probability that he has a car is 0.49 while the probability that he has either a computer or a car is 0.94. Find the probability that the student has both. A) 0.46 B) 0.05 C) 0.84 D) 0.43 11. Determine the number of all possible outcomes of guessing the last three digits in a telephone number if repetition of digits is allowed. A) 30 B) 100 C) 1000 D) 20 12. How many different ways can 4 tickets be selected from 10 tickets if each ticket wins a different prize? A) 270 B) 720 C) 5040 D) 120 Page 1
Use the following to answer questions 13-16: Suppose you have the following data Marital Status Doctors Technicians Nurses Total Married 10 12 10 32 Not Married 5 13 10 28 Total 15 25 20 60 13. The probability that the employee is a doctor is... A) 10/60 B) 10/15 C) 10/32 D) 15/60 14. The probability that the employee is a doctor and not married is... A) 5/60 B) 28/60 C) 5/28 D) 5/15 15. The probability that the employee is a doctor or married is... A) 37/60 B) 10/60 C) 15/60 D) 32/60 16. The probability that the employee is a nurse given that he is not married is... A) 10/60 B) 10/28 C) 10/20 D) 28/60 Use the following to answer questions 17-18: The table below shows the number of earned degrees in the year 2008 in a university by level and gender. A person who earned a degree in the year 2008 from this university is randomly selected. Find the probability of selecting someone who Male Female Level of Degree Bachelor's 300 200 Master's 35 15 17. earned a master's degree or is a female. A) 0.7 B) 0.45 C) 0.64 D) 0.48 18. is a female given that the person earned a bachelor's degree. A) 0.4 B) 0.67 C) 0.36 D) 0.6 Page 2
Use the following to answer questions 19-20: Two dice are rolled. Let X represents the summation of the two faces that will appear. Die 2 Die 1 Sums 1 2 3 4 5 6 1 2 3 4 5 6 7 2 3 4 5 6 7 8 3 4 5 6 7 8 9 4 5 6 7 8 9 10 5 6 7 8 9 10 11 6 7 8 9 10 11 12 19. The probability of X= 4 is... A) 0.083 B) 0.833 C) 0 D) 0.028 20. The probability of X=15 is... A) 0.056 B) 0.028 C) 0.083 D) 0 21. A box contains 3 red balls and 5 black balls. 4 balls are selected with replacement. The standard deviation of the number of red balls that will be obtained is... A) 0.938 B) 5 C) 4 D) 0.968 22. A die is rolled 5 times. The probability of getting a number 4 one time only is... A) 0.402 B) 0.167 C) 0.015 D) 0.386 23. If X is a discrete random variable with probability distribution of X is... A) 1.732 B) 2 C) 4 D) 1.141 2 X P X ( ) 6and 2. The variance for the 24. The outcomes of each trial in a binomial experiment... A) are unlimited B) are independent C) are dependent D) must be fixed 25. It has been found that 6% of all automobiles on the road have defective brakes. If 5 automobiles are stopped and checked by the state police, find the probability that at least one will have defective brakes. A) 0.734 B) 0.0127 C).9872 D) 0.266 Use the following to answer questions 26-28: If a random variable X can have one of three values -1, 0, 1 and each value is Not equally likely, than the probability distribution for X is X -1 0 1 P(X) 0.3 --- 0.5 26. P(X=0) is... A) 0.3 B) 0.2 C) 0.0 D) 0.8 27. The mean value is... A) 0.2 B) 1 C) 0 D) 0.5 Page 3
28. The variance value is... A) 0.76 B) 0.40 C) 0.80 D) 0.20 Use the following to answer questions 29-32: In a certain population 10% of the population is color blind. If a random sample of 3 people is drown from this population, find 29. the probability that exactly one is color blind. A) 0.243 B) 0.165 C) 0.466 D) 1.132 30. the probability that at least one will be color blind. A) 0.281 B) 0.271 C) 0.729 D) -0.132 31. the probability that at most one will be color blind. A) 0.2187 B) 0.1651 C) 0.972 D) 0.948 32. The variance of the number of color blind is... A) 3.00 B) 0.27 C) 1.20 D) 2.00 Page 4
Answer Key 1. A 2. D 3. C 4. B 5. B 6. B 7. B 8. C 9. C 10. A 11. C 12. C 13. D 14. A 15. A 16. B 17. B 18. A 19. A 20. D 21. D 22. A 23. B 24. B 25. D 26. B 27. A 28. A 29. A 30. B 31. C 32. B Page 5