Chapter 9, Problem 9.66CYU

A pooled variance estimate is useful for two-sample hypothesis tests of a normal mean when the underlying population variances can be considered equal.  True or  False?

A pooled variance estimate is useful for two-sample hypothesis tests of a normal mean when the underlying population variances are considered unequal. True False

The forced vital capacity (FVC) is often used by physicians to assess a person's ability to move air in and out of their lungs. It is the maximum amount of air that can be exhaled after a deep breath. A researcher wants to perform a hypothesis test to determine whether the mean forced vital capacity for adults who are smokers is less than the mean forced vital capacity for adults who are former smokers. He will use a paired sample to determine whether forced vital capacity increases, on average, when adults stop smoking. Identify the two populations for the proposed hypothesis test.