The revised guidelines from the National High Blood Pressure Education Program define normal blood pressure as readings below 120/80 millimeters of mercury (The New York Times, May 14, 2003). Prehypertension is suspected when the top number (systolic) is between 120 and 139 or when the bottom number (diastolic) is between 80 and 90. A recent survey reported that the mean systolic reading of Canadians is 125 with a standard deviation of 17 and the mean diastolic reading is 79 with a standard deviation of
10. Assume that diastolic as well as systolic readings are normally distributed.
a. What proportion of Canadians are suffering from prehypertension caused by high diastolic readings?
b. What proportion of Canadians are suffering from prehypertension caused by high systolic readings?