In a recent study, the Centers for Disease Control and Prevention reported that diastolic blood pressures of adult women in the United States are approximately normally distributed with mean 80.5 and standard deviation 9.9.

For parts (a) and (c), make sure to draw a standard normal curve and shade the appropriate areas.

a) What proportion of women have blood pressures lower than 75?

b) Michelle’s diastolic blood pressure is in the 85th percentile of all adult women. What is her blood pressure?

c) If a group of 25 women is selected, what’s the probability that the mean diastolic blood pressure of these 25 women is lower than 75?