A special diet is intendend to reduce cholesterol of patients at risk of heart disease. If the diet is effective, the target is to have the average cholesterol of this group be below 200. After six months on the diet, a simple random sample of 41 patients at risk for heart disease had an average cholesterol of x=192, with standard deviation s=21. Is this sufficient evidence at the a=0.05 (1 tail) levl of significance to state that the diet is effective in meeting the target? Assume the distribution of the cholesterol for patients in this group is approximately Normal. Find a 95% confidence interval for the average cholesterol of patients at risk fo r heart disease who have been on the diet for 6 months.