Blood pressure (BP) in childhood tends to increase with age, but differently for
ID: 3230602 • Letter: B
Question
Blood pressure (BP) in childhood tends to increase with age, but differently for boys and girls. Suppose that for both boys and girls, mean systolic blood pressure is 95 mm Hg per year up to the age of 13. Furthermore, starting at age 13, the mean increase by 2 mm Hg per year for boys and 1 mm Hg per year for girls up to the age of 18. Finally, assume that blood pressure is normally distributed and that the standard deviation is 12 mm Hg for all age-sex groups. What is the probability that an 11-year-old boy will have an SBP greater than 130 mm Hg?
Explanation / Answer
= 95, = 12, x = 130
z = (x - )/ = (130 - 95)/12 = 2.9167
P(x > 130) = P(z > 2.9167) = 0.0018