1. The normal range for cholesterol for an adult is 120 - 240mg/dl. A study found that the total cholesterol level for American adults has a mean of 159.2mg/dl and 84.1 of adults have a cholesterol level below 200mg/dl. Assuming that cholesterol level is normally distributed;
a. Determine the standard deviation of this distribution
b. What are the quartiles (the 25% and 75% values) of this distribution?
c. What is the value of the cholesterol level that exceeds 90% of the population?
d. An adult is at moderate risk if cholesterol level is more than one but less than two standard deviations above the mean. What percentage of the population is at moderate risk according to this criterion?
e. An adult is at high risk if cholesterol level is more than two standard deviations above the mean. What percentage of the population is at high risk?
f. An adult is at low risk if cholesterol level is one standard deviations or more below the mean. What percentage of the population is at low risk?