Question

Construct the indicated confidence interval for the population mean of each data set. If it is possible to construct a confidence interval, justify the distribution you used. If it is not possible, explain why.

(a) In a random sample of 40 patients, the mean waiting time at a dentist’s office was 20 minutes and the standard deviation was 7.5 minutes. Construct a 95% confidence interval for the population mean.

(b) In a random sample of 20 people, the mean tip that they said they would leave after a $30 meal was $3.75 and the standard deviation was $0.25. Construct a 99% confidence interval for the population mean.

(c) In a random sample of 15 cereal boxes, the mean weight was 11.89 ounces. Assume the weights of the cereal boxes are normally distributed and the population standard deviation is 0.05 ounce. Construct a 90% confidence interval for the population mean.

Answer 1

Thank you.