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Study Quiz The Normal Distribution

Mathematics of Data Management 12 > Student Centre > Chapter 8 > Study Quiz The Normal Distribution

Preview Study Quiz The Normal Distribution

Question 1
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Which of the following would be likely to follow a uniform distribution?
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Question 2
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The following waiting times and frequencies were recorded for customers checking out at a grocery store:Select an appropriate distribution, and determine the mean waiting time in minutes.
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Question 3
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The time taken to clean up the Mt. Etna Pizza Parlour after it closes follows a normal distribution with a mean of 30 min and a standard deviation of 5 min. What is the probability that the cleanup crew will complete the job in less than 20 min?
Choose one answer.
Question 4
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The students applying to a computer engineering program at a university have a mean average of 85 with a standard deviation of 6. The admissions committee will only consider students in the top 20%. What cut-off mark should the committee use?
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Question 5
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The refractive error, in diopters, of a sample of 20 students in a school is shown below.Assuming a normal distribution, and using the sample mean and standard deviation, estimate the probability that a student will have a refractive error of less than –1 or greater than +1, and hence will require corrective lenses.
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Question 6
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An advertisement for jelly beans claims "At least 100 beans in every box.". The machine used to fill the boxes has been found to fill boxes with a mean of 108 beans and a standard deviation of 3 beans. What is the probability that the advertising claim is true?
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Question 7
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A company that makes digital watches finds that 2% of its watches fail within the warranty period and must be replaced. The company has sold a shipment of 10 000 watches to a major retail chain store. Use the normal approximation to the binomial distribution to determine the probability that 300 or more watches from this shipment will fail.
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Question 8
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A model of engine used in small aircraft has a mean life of 2000 h of operation with a standard deviation of 100 h. Each year the engine manufacturer collects data on the life of 100 engines. What is the mean and the standard deviation of these samples?
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Question 9
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A candidate working towards a doctorate in labour relations hypothesizes that membership in trade unions increases during an economic recession. Historically, 18% of the workers in the city of Big Apple belong to a trade union. She interviewed 1000 workers during a recession, and found that 200 of them belonged to a trade union. What is the probability that this result occurred by chance, and that the real rate in the city has not changed?
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Question 10
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A manufacturer of computer hardware knows that the life of its hard drives has a standard deviation of 2400 h. Over the past three years, the mean life, based on a sample of 900 hard drives, was 16 000 h of use. The 95% confidence interval for the actual mean life of the drives is
Choose one answer.