A researcher wants to construct a 99% confidence interval to estimate the true mean age of the people who are part of a clinical trial testing the effectiveness of a new migraine medication. A simple random sample of size 15 is taken, producing a sample mean age of 36.7 years and a sample standard deviation of 5.6. If these ages are normally distributed, then the appropriate reliability coefficient for this confidence interval would be а. A. t= 2.9769 B. z = 2.576 C. t= 2.9467 D. t= 2.624 b. If the population standard deviation is 7.3 years, then the appropriate reliability coefficient for this confidence interval would be A. z = 1.96 B. t= 2.7239 C. z = 2.576 D. t= 2.439 . To estimate µ, the mean salary of full professors at American colleges and universities (which is normally distributed), you obtain the salaries of a simple random sample of 20 full professors. The sample mean was found to be $73,220, and the sample standard deviation is $4400. What is the value of the reliability coefficient for a 95% confidence interval foru when calculating the margin of error for this confidence interval? A. t= 1.7247 В. Z3 1.96 C. t= 1.7291 D. t= 2.0930

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