Choosing a Distribution In Exercises 31-36, use the standard normal distribution or the t-distribution to construct a 95

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Choosing A Distribution In Exercises 31 36 Use The Standard Normal Distribution Or The T Distribution To Construct A 95 1 (80.3 KiB) Viewed 60 times

Choosing a Distribution In Exercises 31-36, use the standard normal distribution or the t-distribution to construct a 95% confidence interval for the population mean. Justify your decision. If neither distribution can be used, explain why. Interpret the results. If convenient, use technology to construct the confidence interval. 31. Body Mass Index In a random sample of 50 people, the mean body mass index (BMI) was 27.7 and the standard deviation was 6.12. (Adapted from Centers for Disease Control) 32. Mortgages In a random sample of 15 mortgage institutions, the mean interest rate was 3.57% and the standard deviation was 0.36%. Assume the interest rates are normally distributed. (Adapted from Federal Reserve) 33. Sports Cars: Gas Mileage The gas mileages (in miles per gallon) of 45 randomly selected sports cars are listed. 21 30 19 20 21 24 18 24 27 20 22 30 25 26 23 22 17 21 24 22 20 24 21 20 18 20 21 20 27 21 20 20 19 23 17 20 22 19 15 24 19 19 25 22 25 34. Yards Per Carry In a recent season, the population standard deviation of the yards per carry for all running backs was 1.21. The yards per carry of 20 randomly selected running backs are listed. Assume the yards per carry are normally distributed. (Source: National Football League) 2.8 3.9 5.0 4.4 3.3 3.8 4.8 4.9 3.8 4.2 3.9 3.6 4.0 3.7 6.0 7.2 4.8 2.9 5.3 4.5 35. Hospital Waiting Times In a random sample of 19 patients at a hospital's minor emergency department, the mean waiting time before seeing a medical professional was 23 minutes and the standard deviation was 11 minutes. Assume the waiting times are not normally distributed. 36. Hospital Length of Stay In a random sample of 13 people, the mean length of stay at a hospital was 6.2 days. Assume the population standard deviation is 1.7 days and the lengths of stay are normally distributed. (Adapted from American Hospital Association)