Serum cholesterol is an important risk factor for coronary disease. Suppose that serum cholesterol is approximately normally distributed with mean 216.8 mg/dL and standard deviation 50.61 mg/dL.

1. Cholesterol levels in the top 15% are classified as high enough to warrant risk for heart disease. What cholesterol level corresponds to this cut-off?
   • z =
   • cholesterol = mg/dL
2. Suppose cholesterol levels in the bottom 37% are classified as normal. What cholesterol level corresponds to a normal reading?
   • z =
   • cholesterol = mg/dL
3. Between what two values do the middle 46% of cholesterol readings fall?
   • z = +
   • between mg/dL and mg/dL