1) Let the following sample of 8 observations be drawn from a normal population with unknown mean and standard deviation: 23, 19, 14, 26, 17, 28, 11, 22. a. Calculate the sample mean and the sample standard deviation. Round to 2 decimal places. b. Construct the 80% confidence interval for the population mean. Round to 3 decimal places. What does it mean to be 80% confident ? c. Construct the 90% confidence interval for the population mean. Round to 3 decimal places. What does it mean to be 90% confident ?

2) Using traditional methods, it takes 8.8 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 27 students and observed that they had a mean of 8.6 hours with a variance of 2.56. State the null and alternative hypotheses and perform Hyp. testing using = 0.1, 0.05 and 0.01. Assume the population distribution is approximately normal. 3) An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such that it would produce a mean pressure of 4.1 pounds/square inch. It is believed that the valve performs above the specifications. The valve was tested on 26 engines and the mean pressure was 4.5 pounds/square inch with a variance of 0.64. State the null and alternative hypotheses and perform Hyp. testing using = 0.1, 0.05 and 0.01. Assume the population distribution is approximately normal.

4) CNN/Money reports that the mean cost of a speeding ticket, including court fees, was $150.00 in 2002. A local police department claims that this amount has increased. To test their claim, they collect data from a simple random sample of 160 drivers who have been fined for speeding in the last year, and find that they paid a mean of $154.00 per ticket. Assume that the population standard deviation is $17.54. Write the Hypothesis , Find the Z_sample, p-value and compare with = 0.1, 0.05 and 0.01

5) A national business magazine reports that the mean age of retirement for women executives is 61.0. A women's rights organization believes that this value does not accurately depict the current trend in retirement. To test this, the group polled a simple random sample of 95 recently retired women executives and found that they had a mean age of retirement of 61.5. Assume the population standard deviation is 2.5 years. Write the Hypothesis , Find the Z_sample, p-value and compare with = 0.1, 0.05 and 0.01 6) Find the line of regression Y on X for the following data:(Round your answer to 3rd decimal place) X : 4; 6; 7; 8; 16 Y : 15; 12; 7; 9; 5