18. One of the findings of a group of marketing research students is that 47% of working mothers hold full-time jobs. If a random sample of 40 working mothers is drawn, what is the probability that: a. exactly 10 mothers will hold full-time jobs? b. at most 5 mothers will hold full-time jobs? c. at least 36 mothers will hold full-time jobs?

18. One of the findings of a group of marketing research students is that 47% of working mothers hold full-time jobs. If a random sample of 40 working mothers is drawn, what is the probability that: a. exactly 10 mothers will hold full-time jobs? b. at most 5 mothers will hold full-time jobs? c. at least 36 mothers will hold full-time jobs?

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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5. Big babies: The Centers for Disease Control and Prevention reports that 25% of baby boys 6-8 months old in the United States weigh more than 20 pounds. A sample of 150 babies is studied. a. Approximate the probability that more than 40 weigh more than 20 pounds. b. Approximate the probability that 35 or fewer weigh more than 20 pounds. c. Approximate the probability that the number who weigh more than 20 pounds is G 20
21. A survey involving 600 Democrats, 400 Republicans and 200 Independents asked the question: "Do you favor or oppose eliminating taxes on dividends paid to shareholders?" The following results were obtained: Answer Democrats, % Republicans, % Independents, % Favor 29 66 48 Орpose 71 34 52 What is the probability that a person selected at random from this survey answered "favor"?
6. Clinical trials have shown that 90% of the patients with severe migraine experience relief of their pain after taking the drug Nimodipine. Suppose 15 migraine patients try Nimodipine. a. What is the probability all of the patients experience relief? b. What is the probability only 10 patients experience relief? What is the probability at least 12 patients experience relief? d. What is the probability at most 10 patients experience relief? e. How many are expected to experience relief?
10.A hotel claims that 50% of its customers are very satisfied with its service. Answer the following questions based on a random sample of ten customers: What is the probability that exactly five customers are very satisfied? What is the probability that more than six customers are very satisfied? What is the probability that less than four customers are very satisfied?
4.The mortality rate for a certain disease is 25%. A random sample of twelve patients with this disease is selected. a.What is the probability that exactly half of the patients selected will die from the disease? b.What is the probability that at least two of the twelve patients will die from the disease?
3. An airline tracks data on the flight arrivals. Over the past 6 months, 65 flights on one route around early, 130 arrived on time, 15 were late, and 30 were cancelled. A. What is probability the flight is early? On time? Late? Canceled? B. Are thes outcomes exclusive? C. What id the probability that a flight is either early or on time?
10. According to a Los Angeles Medical Malpractice Law Firm, there are on average 12,414 cases of medical malpractice reported to the NPDB annually. Of these, approximately 5,342 are due to negligence. a. Calculate the probability that an individual randomly selected medical malpractice report is due to negligence. b. Calculate the probability that an individual randomly selected medical malpractice report is not due to negligence. C. It 4 different malpractice suits were randomly selected, what is the probability that all four were not due to negligence.
3. Assume that 12% of people are left-handed. You are trying to find 3 left-handed individuals to interview for an article. Assuming that everyone you approach is willing to be interviewed ... a) what is the probability that you need to approach exactly 6 people to find 3 left-handed individuals? b) what is the probability that you need to approach 6 or more people to find 3 left-handed individuals? c) what is the expected value of the number of individuals that you will need to approach to find 3 left- handed individuals?
12. A survey conducted discovered that 63% of all Americans are overweight. Suppose that a number of randomly selected Americans are weighed. The following table may (or may not) be useful: k 0 1 2 3 4 1 4 6 4 1 4Ck (a) Find the probability that the 4th person weighed is the first person to be overweight. (b) Find the probability that it takes less than 4 people to observe the first overweight person. (c) Find the expected value and variance of the number of Americans that would have to be weighed in order to find the first person that was overweight.