Question: An automobile dealer has an inventory of 400 used cars
An automobile dealer has an inventory of 400 used cars. To estimate the mean mileage of this inventory, she intends to take a simple random sample of used cars. Previous studies suggest that the population standard deviation is 10,000 miles. A 90% confidence interval for the population mean must extend 2,000 miles on each side of its sample estimate. How large of a sample size is necessary to satisfy this requirement?
Answer to relevant QuestionsA country club wants to poll a random sample of its 320 members to estimate the proportion likely to attend an early-season function. The number of sample observations should be sufficiently large to ensure that a 99% ...Everyone knows that exercise is important. Recently, employees of one large international corporation were surveyed and asked, How many minutes do you spend daily on some form of rigorous exercise? From a random sample of 25 ...Dr. Mihaela Sabou wants to estimate the average length of a hospital stay (number of days) for patients with a certain infectious disease. From a random sample of 25 patient records, she finds that the average number of days ...What is the typical age of a person who renews his or her driver’s license online? From a random sample of 460 driver’s license renewal transactions, the mean age was 42.6 and the standard deviation was 5.4. Compute the ...A manufacturer knows that the numbers of items produced per hour by machine A and by machine B are normally distributed with a standard deviation of 8.4 items for machine A and a standard deviation of 11.3 items for machine ...
Post your question