A serum cholesterol level above 250 milligrams per deciliter (mg/dl) of blood is a risk factor for cardiovascular
disease in humans. At a medical center in St. Louis, a study to test the effectiveness of a new cholesterol
lowering drug was conducted. One hundred people with cholesterol levels between 250 mg/dl and 300 mg/dl
were available for this study. Fifty people were assigned at random to each of two treatment groups. One group
received the standard cholesterol-lowering medication and the other group received the new drug. After taking
the drug for three weeks, the 50 subjects who received the standard treatment had a mean decrease in cholesterol
level of 10 mg/dl with a standard deviation of 8 mg/dl, and the 50 subjects who received the new drug had a
mean decrease of 18 mg/dl with a standard deviation of 12 mg/dl.
Does the new drug appear to be more effective than the standard treatment in lowering mean cholesterol level?
Give appropriate statistical evidence to support your conclusion.