Suppose you measured the Serum BUN levels in a sample of several healthy people.  You found that the average was 19.6 mg/dL and the standard deviation was 6.1 mg/dL.  The histogram of the data showed roughly the bell curve shape.  What percent of the whole population of healthy people has Serum BUN levels between 13.5 and 25.7 mg/dL?

Please select the single best answer