1 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. Assume 50 random samples of the same sample size are taken from a population, and a 90% confidence interval is constructed from each sample. How many of the intervals would you expect to contain the true population mean? Answer: Round your answer to a whole number value as necessary. For example, 37 would be a legitimate entry. Question 2 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. A sample of 40 country CD recordings of Willie Nelson has been examined. The average playing time of these recordings is 51.3 minutes, and the standard deviation is s = 5.8 minutes. Using an appropriate t-multiplier, construct a 95% confidence interval for the mean playing time of all Willie Nelson recordings. Place your LOWER limit, in minutes, rounded to 2 decimal places, in the first blank. For example, 56.78 would be a legitimate entry. . Place your UPPER limit, in minutes, rounded to 2 decimal places, in the second blank. For example, 67.89 would be a legitimate entry. Question 3 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. You are told that a random sample of 150 people from Iowa has been given cholesterol tests, and 60 of these people had levels over the safe count of 200. Construct a 95% confidence interval for the population proportion of people in Iowa with cholesterol levels over 200. Place your LOWER limit, rounded to 3 decimal places, in the first blank . For example, .678 would be a legitimate entry. Place your UPPER limit, rounded to 3 decimal places, in the second blank . For example, .789 would be a legitimate entry. Question 4 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. The personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. A random sample of 12 employees reveals the following family dental expenses (in dollars): 115, 370, 250, 593, 540, 225, 177, 425, 318, 182, 275, and 228. Construct a 95% confidence interval estimate for the standard deviation of family dental expenses for all employees of this corporation. Place your LOWER limit, in dollars rounded to 1 decimal place, in the first blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 123.4 would be a legitimate entry. Place your UPPER limit, in dollars rounded to 1 decimal place, in the second blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 567.8 would be a legitimate entry. Question 5 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. If a sample has 20 observations and a 95% confidence estimate for f$mu f$ is needed, the appropriate value of the t-multiple required is . Place your answer, rounded to 3 decimal places, in the blank. For example, 4.567 would be a legitimate entry. Question 6 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. A sample of 9 production managers with over 15 years of experience has an average salary of $71,000 and a sample standard deviation of $18,000. Assuming that s = 18,000 is a reasonable estimate for f$sigma f$ what sample size would be needed to ensure that we could estimate the true mean salary of all production managers with more than 15 years experience within $4200 if we wish to be 95% confident? Place your answer, as a whole number, in the blank. Do not use a dollar sign, a comma, or any other stray mark. For examples, 34 would be a legitimate entry. Question 7 of 20 1.0 Points Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. Senior management of a consulting services firm is concerned about a growing decline in the firms weekly number of billable hours. The firm expects each professional employee to spend at least 40 hours per week on work. In an effort to understand this problem better, management would like to estimate the standard deviation of the number of hours their employees spend on work-related activities in a typical week. Rather than reviewing the records of all the firms full-time employees, the management randomly selected a sample of size 51 from the available frame. The sample mean and sample standard deviations were 48.5 and 7.5 hours, respectively. Construct a 90% confidence interval for the standard deviation of the number of hours this firms employees spend on work-related activities in a typical week. Place your LOWER limit, in hours, rounded to 1 decimal place, in the first blank. For example, 6.7 would be a legitimate entry. Place your UPPER limit, in hours, rounded to 1 decimal place, in the second blank. For example, 12.3 would be a legitimate entry. Part 2 of 3 - Question 8 of 20 1.0 Points A food snack manufacturer samples 15 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10.0 and the sample standard deviation is 0.15, find the 95% confidence interval estimate for the true mean. A.(9.96, 10.04) B.(9.68, 10.32) C.(9.97, 10.80) D.(9.92, 10.08) Reset Selection Question 9 of 20 1.0 Points A previous study of nickels showed that the standard deviation of the weight of nickels is 150 milligrams. How many nickels does a coin counter manufacturer need to weigh so that she can be 98% confident that her sample mean is within 25 milligrams of the true average weight of a nickel? A.36 B.196 C.239 D.139 Reset Selection Question 10 of 20 1.0 Points The t- distribution for developing a confidence interval for a mean has _____ degrees of freedom. A.n + 1 B.n C.n - 1 D.n - 2 Reset Selection Question 11 of 20 1.0 Points If you increase the confidence level, the confidence interval ____________. A.decreases B.may increase or decrease, depending on the sample data C.stays the same D.increases Reset Selection Question 12 of 20 1.0 Points A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. What is the 90% confidence interval for the average days worked by employees in all payroll departments? A.301.0 < \f$\mu \f$ < 319.6 B.298.0 < \f$\mu \f$ < 322.6 C.302.2 < \f$\mu \f$ < 318.4 D.314.1 < \f$\mu \f$ < 316.8 Reset Selection Question 13 of 20 1.0 Points The average gas mileage of a certain model car is 26 miles per gallon. If the gas mileages are normally distributed with a standard deviation of 1.3, find the probability that a randomly selected car of this model has a gas mileage between 25.8 and 26.3 miles per gallon. A.0.15 B.0.85 C.0.70 D.0.30 Reset Selection Question 14 of 20 1.0 Points Compute f$P(t_{20}leq -0.95)f$ where t20 has a t-distribution with 20 degrees of freedom. A.0.8233 B.0.5334 C.0.6466 D.0.1767 Reset Selection Question 15 of 20 1.0 Points In a study of elephants a researcher wishes to determine the average weight of a certain subspecies of elephants. From previous studies, the standard deviation of the weights of elephants in this subspecies is known to be 1500 pounds. How many elephants does the researcher need to weigh so that he can be 80% confident that the average weight of elephants in his sample is within 350 pounds of the true average weight for this subspecies? A.39 B.50 C.31 D.166 Reset Selection Question 16 of 20 1.0 Points At a large department store, the average number of years of employment for a cashier is 5.7 with a standard deviation of 1.8 years. If the number of years of employment at this department store is normally distributed, what is the probability that a cashier selected at random has worked at the store for over 10 years? A.0.4916 B.0.9916 C.0.0084 D.0.0054 Reset Selection Question 17 of 20 1.0 Points A sample of 23 European countries found that the variance of life expectancy was 7.3 years. What is the 95% confidence interval estimate for the variance of life expectancy in Europe? A.27.2 < \f$\sigma ^{2}\f$ < 118.3 B.5.6 < \f$\sigma ^{2}\f$ < 10.3 C.4.4 < \f$\sigma ^{2}\f$ < 14.6 D.28.9 < \f$\sigma ^{2}\f$ < 115.0 Reset Selection Question 18 of 20 1.0 Points In constructing a confidence interval estimate for a population mean, when we replace f$sigma f$ with the sample standard deviation (s), we introduce a new source of variability and the sampling distribution we use is: A.t -distribution B.F- distribution C.the normal distribution D.chi-square distribution Reset Selection Part 3 of 3 - Question 19 of 20 1.0 Points The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and f$hat{p}f$ = 0.20 is 0.2341. True False Reset Selection Question 20 of 20 1.0 Points The lower limit of the 95% confidence interval for the population proportion p, given that n = 300; and f$hat{p}f$ = 0.10 is 0.1339. True False Reset Selection