1. A marketing research company desires to know the mean consumption of milk per week among males over age 25. A sample of 512 males over age 25 was drawn and the mean milk consumption was 3.5 liters. Assume that the population standard deviation is known to be 1 liters. Construct the 90% confidence interval for the mean consumption of milk among males over age 25. Round your answers to one decimal place. Answer: Lower endpoint: _______________ Upper endpoint: _______________

2. The following measurements (in picocuries per liter) were recorded by a set of argon gas detectors installed in a research facility: 831.7, 847.2, 820.9, 826.3 Using these measurements, construct a 95% confidence interval for the mean level of argon gas present in the facility. Assume the population is approximately normal.

Step 1. Calculate the sample mean for the given sample data. Round your answer to two decimal places. Answer: ____________________

Step 2. Calculate the sample standard deviation for the given sample data. Round your answer to two decimal places. Answer: ____________________

Step 3. Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places. Answer: ____________________

Step 4. Construct the 95% confidence interval. Round your answer to two decimal places. Answer: Lower endpoint: _______________ Upper endpoint: _______________ 2

3. A research company desires to know the mean consumption of milk per week among males over age 33. They believe that the milk consumption has a mean of 4.4 liters, and want to construct a 90% confidence interval with a maximum error of 0.08 liters. Assuming a standard deviation of 0.8 liters, what is the minimum number of males over age 33 they must include in their sample? Answer: _______________

4. Using traditional methods, it takes 94 hours to receive a basic flying license. A new license training method using Computer Aided Instruction (CAI) has been proposed. A researcher used the technique with 80 students and observed that they had a mean of 92 hours. Assume the standard deviation is known to be 6. A level of significance of 0.05 will be used to determine if the technique performs differently than the traditional method. Is there sufficient evidence to support the claim that the technique performs differently than the traditional method? Perform a Hypothesis Test