Answer
The blood pressure at the feet is $~~1.7\times 10^3~torr$
Work Step by Step
We can find the blood pressure difference between the head and the feet:
$\Delta P = \rho g \Delta h$
$\Delta P = (1.06\times 10^3~kg/m^3)(9.8~m/s^2)(21~m)$
$\Delta P = 2.1815\times 10^5~N/m^2$
$\Delta P = (2.1815\times 10^5~N/m^2)(\frac{7.50\times 10^{-3}~torr}{1~Pa})$
$\Delta P = 1636~torr$
We can find the blood pressure at the feet:
$p_g = 80~torr+1636~torr$
$p_g = 1.7\times 10^3~torr$
The blood pressure at the feet is $~~1.7\times 10^3~torr$
