A company wants to estimate the mean time (in hours) per week for an adult who...
A computer company wants to estimate the hours per week adults use computers at home. In a random sample of 31 adults, the mean length of time a computer was used at home was 5.3 hours. From past studies the company assumes that σ = 0.9 hours. Construct the 90% confidence interval for the population mean. (Round confidence interval values to two decimal places.)
A researcher wants to estimate how many hours per week students who love off campus spend driving to campus. A simple random sample of 84 students had a mean of 5.0 hours of driving. Construct and interpret a 90% confidence interval for the mean number of hours a student drives per week. Assume the population standard deviation is known to be 0.3 hours per week.
A researcher wants to determine a 99% confidence interval for the mean number of hours that adults spend per week doing community service. How large a sample should the researcher select so that the estimate is within 1.4 hours of the population mean? Assume that the standard deviation for time spent per week doing community service by all adults is 3 hours.
A professor wants to estimate how many hours per week her students study. A simple random sample of 56 students had a mean of 19 hours of studying per week. Construct a 98% confidence interval for the mean number of hours a student studies per week. Assume that the population standard deviation is known to be 2.4 hours per week. Round to two decimal places.
The mean number of hours of study time per week for a sample of 559 students is 23. If the margin of error for the population mean with a 99% confidence interval is 1.7, construct a 99% confidence interval for the mean number of hours of study time per week for all students
10 A publisher wants to estimate the mean length of time (in minutes) all adults spend reading newspapers. To determine this estimate the publisher takes a random sample of 15 people and obtains the results below. From past studies, the publisher assumes o is 23 minutes and that the population of times is normally distributed 12 9 10 7 9 8 7 12 12 6 11 9 9 Construct the 90% and 99% confidence intervals for the population mean. Which...
The mean number of hours of part-time work per week for a sample of 526 college students is 28. if the margin of error for the population mean with a 99 % confidence interval is 2.2, construct a 99 % confidence interval for the mean number of hours of part-time work per week for all college students.
- publisher wants to estimate the mean length of time in minutes) all adults spend reading newspapers. To determine this estimate the publisher takes a random sample of 15 people and obtain the results below. From past studies, the bisher assumes als 1.9 minutes and that the population of times is normally distributed 10 12 10 7 10 11 6 7 6 Construct the 90% and 99% confidence intervals for the population mean. Which interval is wider convenient, use technology...
Cholesterol Contents of Cheese 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% confidence interval for the population mean. Assume the population standard deviation is 3.10 milligrams. (b) The sample mean is 29 milligrams. Using the minimum sample size with a 95% level of confidence, does it...
The mean number of hours of study time per week for a sample of 524 high-school students is 27. If the margin of error for the population mean with a 98% confidence interval is 1.7, construct a 98% confidence interval for the mean number of hours of study time per week for all high-school students. Lower endpoint? upper endpoint?