Suppose we know that the standard deviation for new car purchases is $3,528. We survey 301 purchases, which have a mean price of $27,610. Based on this data, what is the upper value of a 95% conden'val for the mean? A pharmaceutical company has a new drug that allegedly lowers blood pressure in people with hypertension. We want to run a study that tests this hypothesis. We gather together a random sample of 43 people with high blood pressure and keep them in a controlled environment for one week. During this week we periodically measure their blood pressure and nd that the readings for the systolic (upper number) have a mean of 140.6 mmHG. It is known that the standard deviation of blood pressure in this population is 10.52 mmHG. We then administer the drug to the patients. Three days later we measure everyone's blood pressure and nd that the mean systolic reading is 134.6 mmHG. What is the z-statistic we calculate to test the hypothesis that the drug lowers drug pressure