# Question: A consumer magazine has contacted a simple random sample of

A consumer magazine has contacted a simple random sample of 33 owners of a certain model of automobile and asked each owner how many defects had to be corrected within the first 2 months of ownership. The average number of defects was x-bar = 3.7, with a standard deviation of 1.8 defects.

a. Use the t distribution to construct a 95% confidence interval for μ = the average number of defects for this model.

b. Use the z distribution to construct a 95% confidence interval for μ = the average number of defects for this model.

c. Given that the population standard deviation is not known, which of these two confidence intervals should be used as the interval estimate for μ?

a. Use the t distribution to construct a 95% confidence interval for μ = the average number of defects for this model.

b. Use the z distribution to construct a 95% confidence interval for μ = the average number of defects for this model.

c. Given that the population standard deviation is not known, which of these two confidence intervals should be used as the interval estimate for μ?

## Answer to relevant Questions

The service manager of Appliance Universe has recorded the times for a simple random sample of 50 refrigerator service calls taken from last year’s service records. The sample mean and standard deviation were 25 minutes ...The average capacity usage for iPhone users has been estimated as 400 megabytes per month. Assuming this finding to be based on a simple random sample of 80 iPhone users, with a sample standard deviation of s = 90 megabytes ...In examining a simple random sample of 100 sales invoices from several thousand such invoices for the previous year, a researcher finds that 65 of the invoices involved customers who bought less than $2000 worth of ...A Zogby poll found that 75% of Americans can name all of The Three Stooges—Moe, Curly, and Larry. Assuming this finding to be based on a simple random sample of 1200 Americans, construct and interpret the 95% confidence ...Suppose that Nabisco would like to determine, with 95% confidence and a maximum likely error of 0.03, the proportion of first graders in Pennsylvania who had Nabisco’s Spoon-Size Shredded Wheat for breakfast at least once ...Post your question