1. According to the National Health and Nutrition Examination Survey, published by the National Center for Health Statistics, the serum (noncellular portion of blood) total cholesterol level of US females 20 years old or older is normally distributed with a mean of 206 mg/dl and a standard deviation of 44.7 mg/dl.
a. Determine the percentage of US females 20 years old or older who have a serum total cholesterol level below 220 mg/dl.
b. Determine the percentage of US females 20 years old or older who have a serum total cholesterol level between 150 mg/dl and 250 mg/dl.
c. What serum total cholesterol level would the 90thpercentile correspond to (the top 10% highest serum total cholesterol levels are above what value)?