Refer to the blood pressure distribution of Exercise 3.S.9. Suppose four men are selected at random from the population. Find the probability that
(a) All four have blood pressures higher than 140 mm Hg.
(b) Three have blood pressures higher than 140, and one has blood pressure 140 or less.
Exercise 3.S.9
The density curve shown here represents the distribution of systolic blood pressures in a population of middle-aged men. Areas under the curve are shown in the figure. Suppose a man is selected at random from the population, and let Y be his blood pressure.