Suppose that pregnancies for all women are known to have a mean duration of 282 days and a standard deviation of 9 3 days doctor wants to compare the duration of pregnancy for women who exercise to the duration of pregnancy for all women To this she selects a random sample of 82 pregnant women who exercise and finds that the mean duration of pregnancy for thes women is 283 days The doctor plans to use a one sample z test to determine whether or not the mean duration of pregnancy for women who exercise differs from the mean duration of pregnancy for all women Choose the appropriate null and alternative hypotheses for such a test O Ho 282 days and H 282 days Ho 282 days and H 282 days 283 days and H 283 days O Ho O Ho 282 days and H 282 days O Hox 282 days and H 282 days