LAB 9: Hypothesis Testing for a Population Mean
Purpose: In this lab, we will use Excel to test a hypothesis about a population mean. In
particular, we will use a data set on body temperatures of healthy adults to test the claim that
the typical (i.e. average) temperature with humans is 98.6 degrees Fahrenheit. Open the excel
worksheet “nortemp”. Column 1 has the body temperatures of the n=130 healthy adults.
Column 2 is an indicator for males (1=male) and females (2=female). Column 3 gives the pulse
rate. Fill out these sheets and turn them in.
hypothesis
H0: versus H1: ≠ 98.6 (Note – this is a two-tailed test).
Fill out this worksheet by doing the following parts:
1. For this test, what is a type I error? Give the answer in the context of the problem.
2. For this test, what is a type II error? Give the answer in the context of the problem.
3. To test the hypothesis at significance level  = 0.05, determine the critical region by
drawing the t-density and shading the critical region.
4. Compute the sample mean by typing in an empty cell “=AVERAGE(A2:A131)”
𝑥̅ =_________
5. Compute the sample standard deviation by typing in an empty cell “=STDEV(A2:A131)”
s = ________
6. Compute the t-test statistic manually
𝑥̅ −𝜇
t=
=
𝑠/√𝑛
7. Does the t-test statistic fall in the critical region from #3? (Circle one) YES NO
8. Write a sentence giving the conclusion to this hypothesis test in the context of the
problem (be sure to specify the significance level in your conclusion).
9. Compute the P-value for this test using the “tdist” function in excel. To use the tdist
function, click on an empty cell and type in “=TDIST(5.458,129,2)”.
p-value = ____________________________
10. Based on the p-value, does it seem plausible that the average body temperature is 98.6?
Explain.