A clinical trial is being planned to investigate the effect of a new experimental drug designed to reduce total serum cholesterol.

A clinical trial is being planned to investigate the effect of a new experimental drug designed to reduce total serum cholesterol. Investigators will enroll participants with total cholesterol levels between 200-240, they will be randomized to receive the new drug or a placebo and followed for two months, and the total cholesterol will be measured. Investigators plan to run a test of hypothesis and want 80% power to detect a difference of 10 points in mean total cholesterol levels between groups. How many participants must be enrolled in the study? Assume that the standard deviation of total cholesterol is 18.5.