A special diet is intended to reduce the 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, an SRS of 50 patients at risk for heart disease had an average cholesterol of 192, with standard deviation s = 21. Is this sufficient evidence that the diet is effective in meeting the target? Assume the distribution of the cholesterol for patients in this group is approximately Normal with mean .

A 95% confidence interval for the average cholesterol of patients at risk for heart disease who have been on the diet for six months is

Select one:

a.

192 8.23.

b.

192 7.54.

c.

192 10.61.

d.

192 5.97.