A medical doctor wants to reduce blood pressure in his hypertensive patients by teaching them to meditate. He finds that the mean systolic blood pressure for the population of Stage 2 hypertensive patients (those with high blood pressure) is 180 mmHG (=180) with a standard deviation of 18 mmHG (=18). After teaching a sample of 9 patients to mediate, he obtains a sample mean of 175. If he taught all his patients to meditate, could it reduce their average blood pressure? To answer this, he decides to calculate a 99% confidence interval for this average.

1. What are the critical values of Z? (+/-)
2. What is the standard error of the mean?
3. What is the probability of obtaining this mean(175 mmHG) or lower?
4. What is the margin of error? (half the width of the CI)
5. What is the confidence interval? Answer with the following format: (xxx.xx,xxx.xx)