U2.L5.HW: Quadratic Equations: Question 40

Question

A person's systolic blood pressure, which is measured in millimeters of mercury (mm Hg), depends on a person's age, in years. The equation:

P = 0.007y² - 0.03y + 118

gives a person's blood pressure, P, at age y years.

A.) Find the systolic pressure, to the nearest tenth of a millimeter, for a person of age 44 years.

B.) If a person's systolic pressure is 134 mm Hg, what is their age (rounded to the nearest whole year)?

Answer 1

.007(44)^2 - .03(44) + 118

= 13.552 - 1.32 + 118

= 12.232 + 118

= 130.232 mm Hg

134 = .007y^2 -.03y + 118

.007y^2 -.03y -16= 0

use the quadratic formula

y = .03/.014 + (1/.014)sqr(.03^2 +4(.007)(16))

y = (.03 + sqr(.0009 + .448))/.014

y = (.03 + sqr(.4489))/.014

y = .70/.014 = .1/.002 = 100/2 = 50 years old