Next set of questions: This will be 10 questions as well>....
Pilots who cannot maintain regular sleep hours due to their work schedule often suer from insomnia. A recent study on sleeping patterns of pilots focused on quantifying deviations from regular sleep hours. A random sample of 19 commercial airline pilots was interviewed, and the pilots in the sample reported the time at which they went to sleep on their most recent working day. The study gave the sample mean and standard deviation of the times reported by pilots, with these times measured in hours atter midnight. (Thus, if the pilot reported going to sleep at 11 pm, the measurement was -1.) The sample mean was 0.5 hours, and the standard deviation was 1.8 hours. Assume that the sample is drawn from a normally distributed population. Find a 95% condence interval for the population standard deviation, that is, the standard deviation of the time (hours after midnight) at which pilots go to sleep on their work days. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places. (If necessary, consult a list of formulas.) What is the lower limit of the 95% condence interval? I] What is the upper limit ofthe 95% condence interval? I] Next >> ' | Explain l The scores on an examination in economics are approximately normally distrihuted with mean 500 and an unknown standard deviation, The following is a random sample of scores from this examination. 422. 422. 454. 488, 530. 542 E 52nd dam in Excel Find a 99% condence interval for the population standard deviation, Then oomplete the table below, Carry your intermediate computations to at least three decimal places, Round your answers to at least two decimal places, (If necessary, consult a list of formulas) What is the lower limit of the 99% condence interval? m what is the upper limit of the 99% condence interval? '1 Next >> ' | Explain l Suppose that a researcher is interested in estimating the mean systolic blood pressure, H, of executives of major oorporations. He plans to use the blood pressures of a random sample of executives of major corporations to estimate H Assuming that the standard deviation of the population of systolic blood pressures of executives of major corporations is 27 mm Hg. what is the minimum sample size needed for the researcher to be 95% condent that his estimate is within 5 mm Hg of H '2 Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satises the requirements). (If necessary, consult a list of formulas.) j Next >> j | Email | Many college graduates who are employed lulltime have longer than 40hour work weeks. Suppose that we wish to estimate the mean number of hours, H , worked per week by college graduates employed fulletime. We'll choose a random sample of college graduates employed full-time and use the mean of this sample to estimate [4 . Assuming that the standard deviation of the number of hours worked by college graduates is 6.00 hours per week, what is the minimum sample size needed in order for us to be 99% contident that our estimate is within 1.3 hours per week of H ? Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satises the requirements). (If necessary, consult a list of formulas.) ' Next >> l | Explain l Executives of a supermarket chain are interested in the amount of time that customers spend in the stores during shopping trips, The executives hire a statistical consultant and ask her to determine the mean shopping time, [4 , of customers at the supermarkets, The consultant will collect a random sample of shopping times at the supermarkets and use the mean of these shopping times to estimate H . Assuming that the standard deviation of the population of shopping times at the supermarkets is 27 minutes, what is the minimum sample size she must collect in order for her to be 90% condent that her estimate is within 5 minutes of H ? Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satises the requirements), (If necessary, consult a list of formulas.) ' Next >> ' | Explain l
