Chapter 10 Inferences on Two Samples 10.2 Inference about Two Means: Independent Sampling

Step 4: Compare the critical value with the test statistic:

Step 5 : State the conclusion.

EXAMPLE Comparing Two Means: Independent Sampling A researcher wanted to know whether “state” quarters had a weight that is more than “traditional” quarters. He randomly selected 18 “state” quarters and 16 “traditional” quarters, weighed each of them and obtained the following data.

The degrees of freedom used to determine the critical value(s) presented in the last example are conservative. Results that are more accurate can be obtained by using the following degrees of freedom:

Lower Bound = Upper Bound =

EXAMPLE. Constructing a Confidence Interval EXAMPLE Constructing a Confidence Interval about the Difference of Two Means Construct a 95% confidence interval about the difference between the weight of “state” quarters and “traditional” quarters.