Based on a random sample of 100 employees at a large firm, a 95% confidence interval is calculated
for the mean age of all of the firm's employees. The interval is (34.5 years, 47.2 years).
a. What was the sample mean? (Hint: Where does the point estimate fall within a confidence
interval ?)
b. Determine the margin of error.
6. It has long been reported that normal human body temperature follows a normal distribution with a
mean of 98.6 degrees Fahrenheit. But is the mean really 98.6°F? A group of medical researchers
measured the body temperature of a random sample of 18 healthy individuals. After the researchers
made their measurements, they entered the data into a statistical software package and ran the
appropriate statistical test. The output generated from this test is printed below. Based on this output,
what should they conclude and why?
T-Test of the Mean
Test of mu = 98.60 vs mu not = 98.60
Variable N Mean StDev SE Mean T P
TEMP 18 98.2167 0.68363 0.16113 -2.39 0.029