You are given the sample mean and the sample standard deviation. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 95% confidence interval for the population mean. Interpret the results.
In a random sample of eight people, the mean commute time to work was 35.5 minutes and the standard deviation was 7.2 minutes.
> You wish to estimate, with 90% confidence, the population proportion of U.S. adults who eat fast food four to six times per week. Your estimate must be accurate within 3% of the population proportion. a. No preliminary estimate is available. Find the mi
> You wish to estimate, with 99% confidence, the population proportion of U.S. adults who support labeling legislation for genetically modified organisms (GMOs). Your estimate must be accurate within 2% of the population proportion. a. No preliminary esti
> You wish to estimate, with 95% confidence, the population proportion of U.S. adults who think Congress is doing a good or excellent job. Your estimate must be accurate within 4% of the population proportion. a. No preliminary estimate is available. Find
> In a survey of 1000 U.S. adults, 490 oppose allowing transgender students to use the bathrooms of the opposite biological sex. Construct a 90% confidence interval for the population proportion of U.S. adults who oppose allowing transgender students to us
> In a survey of 1,626,773 U.S. adults, 49,311 personally identify as lesbian, gay, bisexual, or transgender. Construct a 95% confidence interval for the population proportion of U.S. adults who personally identify as lesbian, gay, bisexual, or transgender
> Construct a 99% confidence interval for the population proportion. Interpret the results. In a survey of 600 United Kingdom teachers, 226 say they would wear a body camera in school.
> In a standardized IQ test, scores are normally distributed, with a mean score of 100 and a standardized deviation of 15. A random sample of 60 people is selected from this population. What is the probability that the mean IQ score of the sample is greate
> Construct a 99% confidence interval for the population proportion. Interpret the results. In a survey of 1000 U.S. adults, 700 think police officers should be required to wear body cameras while on duty.
> Construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals. In a survey of 2241 U.S. adults in a recent year, 650 made a New Year’s resolution to eat healthier.
> Construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals. In a survey of 2241 U.S. adults in a recent year, 1322 say they have made a New Year’s resolution.
> Use the confidence interval to find the margin of error and the sample proportion. (0.087, 0.263)
> Determine whether the statement is true or false. If it is false, rewrite it as a true statement. To estimate the value of p, the population proportion of successes, use the point estimate x.
> Construct the indicated confidence interval for the population mean m using the t-distribution. Assume the population is normally distributed. c = 0.90, x = 12.5, σ = 2.0, n = 6
> Find the margin of error for the values of c, s, and n. c = 0.98, s = 4.7, n = 9
> Find the margin of error for the values of c, s, and n. c = 0.90, s = 2.4, n = 35
> Find the margin of error for the values of c, s, and n. c = 0.99, s = 3, n = 6
> Find the margin of error for the values of c, s, and n. c = 0.95, s = 5, n = 16
> In a standardized IQ test, scores are normally distributed, with a mean score of 100 and a standardized deviation of 15. What is the highest score that would still place a person in the bottom 10% of the scores?
> A company manufactures light bulbs. The company wants the bulbs to have a mean life span of 1000 hours. This average is maintained by periodically testing random samples of 16 light bulbs. If the t-value falls between -t0.99 and t0.99, then the company w
> A company manufactures tennis balls. When its tennis balls are dropped onto a concrete surface from a height of 100 inches, the company wants the mean height the balls bounce upward to be 55.5 inches. This average is maintained by periodically testing ra
> In Exercise 38, does it seem possible that the population mean could be within 10% of the sample mean? Explain.
> Find the critical value tc for the level of confidence c and sample size n. c = 0.98, n = 40
> In Exercise 36, does it seem possible that the population mean could equal half the sample mean? Explain. From Exercise 36: In a random sample of 18 months from June 2008 through September 2016, the mean interest rate for 30-year fixed rate conventional
> Use the standard normal distribution or the t-distribution to construct a 95% confidence interval for the population mean. Justify your decision. If neither distribution can be used, explain why. Interpret the results. In a recent season, the population
> Use the standard normal distribution or the t-distribution to construct a 95% confidence interval for the population mean. Justify your decision. If neither distribution can be used, explain why. Interpret the results. The gas mileages (in miles per gall
> Use the standard normal distribution or the t-distribution to construct a 95% confidence interval for the population mean. Justify your decision. If neither distribution can be used, explain why. Interpret the results. In a random sample of 18 months fro
> Use the standard normal distribution or the t-distribution to construct a 95% confidence interval for the population mean. Justify your decision. If neither distribution can be used, explain why. Interpret the results. In a random sample of 50 people, th
> In Exercise 32, the population mean salary is $61,000. Does the t-value fall between -t0.98 and t0.98?
> In a standardized IQ test, scores are normally distributed, with a mean score of 100 and a standardized deviation of 15. What is the lowest score that would still place a person in the top 5% of the scores?
> The five-year success rate of kidney transplant surgery from living donors is 86%. The surgery is performed on six patients. a. Construct a binomial distribution. b. Graph the binomial distribution using a histogram and describe its shape. c. Find the
> In Exercise 31, the population mean salary is $72,000. Does the t-value fall between -t0.98 and t0.98?
> Use the data set to a. find the sample mean, b. find the sample standard deviation, and c. construct a 98% confidence interval for the population mean. The annual earnings (in dollars) of 40 randomly selected intermediate level life insurance underwri
> Use the data set to a. find the sample mean, b. find the sample standard deviation, and c. construct a 98% confidence interval for the population mean. The annual earnings (in dollars) of 32 randomly selected magnetic resonance imaging technologists
> In Exercise 28, the population mean weekly time spent on homework by students is 7.8 hours. Does the t-value fall between -t0.99 and t0.99?
> Find the critical value tc for the level of confidence c and sample size n. c = 0.99, n = 16
> In Exercise 25, the population mean SAT score is 1020. Does the t-value fall between -t0.99 and t0.99?
> Use the data set to a. find the sample mean, b. find the sample standard deviation, and c. construct a 99% confidence interval for the population mean. Assume the population is normally distributed. The weekly time spent (in hours) on homework for 18
> Use the data set to a. find the sample mean, b. find the sample standard deviation, and c. construct a 99% confidence interval for the population mean. Assume the population is normally distributed. The weekly time (in hours) spent weight lifting for
> Use the data set to a. find the sample mean, b. find the sample standard deviation, and c. construct a 99% confidence interval for the population mean. Assume the population is normally distributed. The grade point averages of 14 randomly selected co
> Use the data set to a. find the sample mean, b. find the sample standard deviation, and c. construct a 99% confidence interval for the population mean. Assume the population is normally distributed. The SAT scores of 12 randomly selected high school
> Find the indicated probabilities using the geometric distribution, the Poisson distribution, or the binomial distribution. Then determine whether the events are unusual. If convenient, use a table or technology to find the probabilities. About 60% of U.S
> You research repair costs of mobile devices and find that the population mean is $89.56. In Exercise 20, does the t-value fall between -t0.95 and t0.95?
> You research prices of cell phones and find that the population mean is $431.61. In Exercise 19, does the t-value fall between -t0.95 and t0.95?
> You research driving distances to work and find that the population standard deviation is 5.2 miles. Repeat Exercise 18 using the standard normal distribution with the appropriate calculations for a standard deviation that is known. Compare the results.
> You research commute times to work and find that the population standard deviation is 9.3 minutes. Repeat Exercise 17 using the standard normal distribution with the appropriate calculations for a standard deviation that is known. Compare the results. F
> You are given the sample mean and the sample standard deviation. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 95% confidence interval for the population mean. Interpret the results.
> Find the critical value tc for the level of confidence c and sample size n. c = 0.95, n = 12
> You are given the sample mean and the sample standard deviation. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 95% confidence interval for the population mean. Interpret the results.
> You are given the sample mean and the sample standard deviation. Assume the population is normally distributed and use the t-distribution to find the margin of error and construct a 95% confidence interval for the population mean. Interpret the results.
> Use the confidence interval to find the margin of error and the sample mean. (16.2, 29.8)
> Find the indicated probabilities using the geometric distribution, the Poisson distribution, or the binomial distribution. Then determine whether the events are unusual. If convenient, use a table or technology to find the probabilities. One out of every
> Use the confidence interval to find the margin of error and the sample mean. (64.6, 83.6)
> Use the confidence interval to find the margin of error and the sample mean. (6.17, 8.53)
> Use the confidence interval to find the margin of error and the sample mean. (14.7, 22.1)
> Construct the indicated confidence interval for the population mean µ using the t-distribution. Assume the population is normally distributed. c = 0.99, x = 24.7, σ = 4.6, n = 50
> Construct the indicated confidence interval for the population mean µ using the t-distribution. Assume the population is normally distributed. c = 0.98, x = 4.3, σ = 0.34, n = 14
> Construct the indicated confidence interval for the population mean µ using the t-distribution. Assume the population is normally distributed. c = 0.95, x = 13.4, σ = 0.85, n = 8
> Find the critical value tc for the level of confidence c and sample size n. c = 0.90, n = 10
> Use the values on the number line to find the sampling error. X = 3.8 µ = 4.27 +++X 3.4 3.6 3.8 4.0 4.2 4.4 4.6
> Find the critical value zc necessary to construct a confidence interval at the level of confidence c. c = 0.97
> Find the critical value zc necessary to construct a confidence interval at the level of confidence c. c = 0.75
> Seventy-seven percent of U.S. college students pay their bills on time. You randomly select five U.S. college students and ask them whether they pay their bills on time. The random variable represents the number of U.S. college students who pay their bil
> Find the critical value zc necessary to construct a confidence interval at the level of confidence c. c = 0.85
> The equation for determining the sample size can be obtained by solving the equation for the margin of error for n. Show that this is true and justify each step. 2. n E E Vn
> Use the finite population correction factor to construct each confidence interval for the population mean. a. c = 0.99, x = 8.6, σ = 4.9, N = 200, n = 25 b. c = 0.90, x = 10.9, σ = 2.8, N = 500, n = 50 c. c = 0.95, x = 40.3, σ = 0.5, N = 300, n = 68
> Determine the finite population correction factor for each value of N and n. a. N = 1000 and n = 500 b. N = 1000 and n = 100 c. N = 1000 and n = 75 d. N = 1000 and n = 50 e. N = 100 and n = 50 f. N = 400 and n = 50 g. N = 700 and n = 50 h. N = 120
> When all other quantities remain the same, how does the indicated change affect the minimum sample size requirement? Explain. a. Increase in the level of confidence b. Increase in the error tolerance c. Increase in the population standard deviation
> When estimating the population mean, why not construct a 99% confidence interval every time?
> A tennis ball manufacturer wants to estimate the mean circumference of tennis balls within 0.05 inch. Assume the population of circumferences is normally distributed. a. Determine the minimum sample size required to construct a 99% confidence interval f
> A soccer ball manufacturer wants to estimate the mean circumference of soccer balls within 0.15 inch. a. Determine the minimum sample size required to construct a 99% confidence interval for the population mean. Assume the population standard deviation
> A beverage company uses a machine to fill half-gallon bottles with fruit juice (see figure). The company wants to estimate the mean volume of water the machine is putting in the bottles within 0.25 fluid ounce. a. Determine the minimum sample size requi
> A paint manufacturer uses a machine to fill gallon cans with paint (see figure). The manufacturer wants to estimate the mean volume of paint the machine is putting in the cans within 0.5 ounce. Assume the population of volumes is normally distributed. a
> The table shows the ages of students in a freshman orientation course. a. Construct a probability distribution. b. Graph the probability distribution using a histogram and describe its shape. c. Find the mean, variance, and standard deviation of the p
> An admissions director wants to estimate the mean age of all students enrolled at a college. The estimate must be within 1.5 years of the population mean. Assume the population of ages is normally distributed. a. Determine the minimum sample size requir
> Find the critical value zc necessary to construct a confidence interval at the level of confidence c. c = 0.80
> A cheese processing company wants to estimate the mean cholesterol content of all one-ounce servings of a type of cheese. The estimate must be within 0.75 milligram of the population mean. a. Determine the minimum sample size required to construct a 95%
> Determine the minimum sample size required when you want to be 99% confident that the sample mean is within two units of the population mean and σ = 1.4. Assume the population is normally distributed.
> Determine the minimum sample size required when you want to be 95% confident that the sample mean is within one unit of the population mean and σ = 4.8. Assume the population is normally distributed.
> Use the information to construct 90% and 99% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. The sodium chloride concentrations (in grams per liter) for 36 randomly selected seawater
> Use the information to construct 90% and 99% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. A group of researchers estimates the mean length of time (in minutes) the average U.S. ad
> Describe how you would construct a 90% confidence interval to estimate the population mean age for students at your school.
> When all other quantities remain the same, how does the indicated change affect the width of a confidence interval? Explain. a. Increase in the level of confidence b. Increase in the sample size c. Increase in the population standard deviation
> In Exercise 38, does it seem possible that the population mean could be less than 100? Explain.
> Determine whether the distribution is a probability distribution. If it is not a probability distribution, explain why. (a) 5 10 15 20 P(x) 0.03 0.09 0.19 0.32 0.37 (b) 1 4 5 6 P(x) 20 10 3. 10 25 3. 2.
> In Exercise 37, does it seem possible that the population mean could be greater than 90°F? Explain.
> In Exercise 36, does it seem possible that the population mean could be within 1% of the sample mean? Explain.
> You construct a 95% confidence interval for a population mean using a random sample. The confidence interval is 24.9 < µ < 31.5. Is the probability that µ is in this interval 0.95? Explain.
> In Exercise 35, does it seem possible that the population mean could equal the sample mean? Explain.
> You are given the sample mean and the population standard deviation. Use this information to construct 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sampl
> You are given the sample mean and the population standard deviation. Use this information to construct 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sampl
> You are given the sample mean and the population standard deviation. Use this information to construct 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sampl
> You are given the sample mean and the population standard deviation. Use this information to construct 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sampl
> Use the confidence interval to find the estimated margin of error. Then find the sample mean. A store manager reports a confidence interval of (244.07, 280.97) when estimating the mean price (in dollars) for the population of textbooks.
> Use the confidence interval to find the estimated margin of error. Then find the sample mean. A government agency reports a confidence interval of (26.2, 30.1) when estimating the mean commute time (in minutes) for the population of workers in a city.
> Find the indicated probabilities using the geometric distribution, the Poisson distribution, or the binomial distribution. Then determine whether the events are unusual. If convenient, use a table or technology to find the probabilities. The mean increas
> Determine the minimum sample size n needed to estimate m for the values of c, σ, and E. c = 0.98, σ = 10.1, E = 2
> Determine the minimum sample size n needed to estimate m for the values of c, σ, and E. c = 0.80, σ = 4.1, E = 2
> Determine the minimum sample size n needed to estimate m for the values of c, σ, and E. c = 0.95, σ = 2.5, E = 1
> For the same sample statistics, which level of confidence would produce the widest confidence interval? Explain your reasoning. a. 90% b. 95% c. 98% d. 99%
> Determine the minimum sample size n needed to estimate m for the values of c, σ, and E. c = 0.90, σ = 6.8, E = 1