1. Getting a good night's sleep is essential for teenage students to perform optimally during school.According to the National Sleep Foundation, high school students need at least 8 hours of sleep foroptimal performance at school the following day. Based on a sleep study of 459 students, a 95%Confidence Interval for the true mean sleeping time (in hours) was calculated to be (7, 7.28) hours.a. Researchers want to test if students, on average, are getting more than the required amount ofsleep to perform optimally at school. State the null and alternative hypothesis in proper notation.b. What conclusion can you make about the null and alternative hypothesis based on the confi-dence interval ?

a) Here are the null and alternative hypotheses stated :Null hypothesis (H₀): The population mean…

Answered: 1. Getting a good night's sleep is…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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To estimate the mean amount of time children spend in physical activities daily,a researcher randomly selects 8 children and records the number of hours theyspend in physical activities in one day. The numbers of hours are: 4.1, 1.2, 4.6,2.4, 3.2, 1.8, 2.4, and 0.7. Obtain a 95% confidence interval of the mean numberof hours that children spend in physical activities.
9. A study of 420,082 cell phone users found that 140 of them developed cancer of the brain or nervous system. Prior to this study of cell phone use, the rate of such cancer was found to be 0.0243% for those not using cell phones. Complete parts (a) and (b). a. Use the sample data to construct a 95% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system. %
A purchasing manager for a large university is investigating which brand of LCD projector to purchase to equip their classrooms. Of major concern is the longevity of the light bulbs used in the projectors. The purchasing manager has narrowed down the choice of projector to two brands, Infocus and Proxima, and wishes to determine if there is any difference between the two brands in the mean lifetime of the bulbs used. The purchasing manager obtained thirteen projectors of each brand for testing over the last several academic terms. The number of hours the bulbs lasted on each of the thirteen projectors is given in the table. Lifetimes of light bulbs (hours) Infocus 830, 867, 1013, 986, 819, 809, 691, 903, 673, 909, 957, 820, 715 Proxima 532, 718, 769, 806, 779, 970, 903, 1043, 947, 792, 841, 752, 689 Send data to calc... v Send data to Excel Assume that the two populations of lifetimes, are normally distributed and that the population variances are equal. Can we conclude, at the 0.01…
2. In a simple random sample of 1200 Americans age 20 and over, 138 of them were found to have Type I diabetes. Round all answers to three decimal places. a) Report a 95% confidence interval for the proportion of all Americans age 20 and over with diabetes. J b) According to the Centers for Disease Control and Prevention, nationally, 10.7% of all Americans age 20 and over have diabetes. Does the confidence interval you found support or refute this claim? Explain.
A study from 2014 found that adults in the US spend an average of 11 hours per day watching, reading, listening to or simply interacting with media. Researchers at UCLA suspect students spend less time engaging media. They grouped UCLA students by class section, randomly selected 20 class sections, and administered a survey to each student in those randomly selected class sections. The following data represents the mean time (in hours) per day spent engaging media for each of the randomly selected classes: 9.5 11.5 6.0 7.5 8 9.5 10.5 11 12 8.2 5 9.5 8.2 9.3 10.8 11 13 8.6 9.5 10.5 What would be the 99% Confidence Interval for mean time (in hours) spent per day engaging media for UCLA students. Do this "by hand", using appripriate symbols/formulas/tables.
A purchasing manager for a large university is investigating which brand of LCD projector to purchase to equip their classrooms. Of major concern is the longevity of the light bulbs used in the projectors. The purchasing manager has narrowed down the choice of projector to two brands, Infocus and Proxima, and wishes to determine if there is any difference between the two brands in the mean lifetime of the bulbs used. The purchasing manager obtained eight projectors of each brand for testing over the last several academic terms. The number of hours the bulbs lasted on each of the eight projectors is given in the table. Lifetimes of light bulbs (hours) Infocus 745, 955, 1085, 756, 901, 839, 858, 931 Proxima 1012, 988, 957, 920, 878, 1130, 657, 743 Send data to calculator Assume that the two populations of lifetimes are normally distributed and that the population variances are equal. Can we conclude, at the 0.01 level of significance, that u, the mean lifetime of light bulbs in Infocus…
8. A confidence interval for estimating the mean An industrial/organizational psychologist wants to improve worker productivity for a client firm, but first he needs to gain a better understanding of the life of the typical white-collar professional. Fortunately, he has access to the 2008 Workplace Productivity Survey, commissioned by LexisNexis and prepared by WorldOne Research, which surveyed a sample of 650 white-collar professionals (250 legal professionals and 400 other professionals). One of the survey questions was, “How many work-related emails do you receive during a typical workday?” For the subsample of legal professionals (n = 250), the mean response was M = 36.7 emails, with a sample standard deviation of s = 23.8 emails. The estimated standard error is sMM? = A-0.085, B-1.341, C-0.095 or D-1.505 (choices to choose from.) . Use the following Distributions tool to develop a 90% confidence interval estimate of the mean number of work-related emails legal…
5. A researcher constructed a 95% confidence interval for the true mean number of years students take to earn a bachelor's degree. His results were (4.319, 4.841). a. What is the point estimate for the average number of years to complete a bachelor's degree? b. Does his interval support or contradict the widely held belief that it takes 4 years to complete a bachelor's degree? Why or why not?
5. a). What is a fundamental difference between the t statistic and a z-score in terms of variability? b). What value is estimated with a confidence interval using the t statistic?
8.2 Question 3). According to the February 2008 Federal Trade Commission report on consumer fraud and identity theft, Arkansas had 1,601 complaints of identity theft out of 3,482 consumer complaints ("Consumer fraud and," 2008). Calculate a 90% confidence interval for the proportion of identity theft in Arkansas.
A study from 2014 found that adults in the US spend an average of 11 hours per day watching, reading, listening to or simply interacting with media. Researchers at UCLA suspect students spend less time engaging media. They grouped UCLA students by class section, randomly selected 20 class sections, and administered a survey to each student in those randomly selected class sections. The following data represents the mean time (in hours) per day spent engaging media for each of the randomly selected classes: 9.5 11.5 6.0 7.5 8 9.5 10.5 11 12 8.2 5 9.5 8.2 9.3 10.8 11 13 8.6 9.5 10.5 What would be the calculator steps to find standard deviaton, rounded to 3 decimal places?
• Example: A sample of 25 physically and mentally healthy males participated in a sleep experiment in which the percentage of each participant's total sleeping time spent in a certain stage of sleep was recorded. • The variance computed from the sample data was 2.25. Construct 95 percent confidence intervals for o².

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