Question 5 (1 point) A drug company wishes to examine if their drug is effective in treating high blood pressure. In the study, the researchers randomly selected 18 volunteers and recorded their blood pressure before taking the drugs. After 12 weeks on the drug, the blood pressure was measured again. The results (mmHg) for 18 volunteers are shown below: Mean Standard Deviation Before 163 16 After 157 12 Differences -6 14.3 (After - Before) Assuming that both populations (before and after the treatment) are normally distributed, what is a 95% confidence interval for the true mean difference (After - Before) in blood pressure