High blood pressure results from constriction of the arteries. To maintain a normal flow rate (flux), the heart has to pump harder, thus increasing the blood pressure. Use Poiseuille's Law to show that if $ R_0 $ and $ P_0 $ are normal values of the radius and pressure in an artery and the constricted values are $ R $ and $ P $, then for the flux to remain constant, $ P $ and $ R $ are related by the equation

$$ \frac{P}{P_0} = (\frac{R_0}{R})^4 $$

Deduce that if the radius of an artery is reduced to three-fourths of its former value, then the pressure is more than tripled.