Answer
$h=713.56m$
Work Step by Step
First we calculate the pressions at the plane and at the ground:
$P_{p}=\rho_{Hg}gh_{Hg,p}=13600\frac{kg}{m^3}*9.81\frac{m}{s^2}*0.690m Hg=92.06kPa$
$P_{g}=\rho_{Hg}gh_{Hg,g}=13600\frac{kg}{m^3}*9.81\frac{m}{s^2}*0.753m Hg=100.46kPa$
So the difference of pressure is:
$\Delta P=100.46kPa-92.06kPa=8.4kPa$
Knowing that: $P=\rho gh$
So: $h=\frac{P}{\rho g}$
Substituting:
$h=\frac{8400Pa}{1.20\frac{kg}{m^3}*9.81\frac{m}{s^2}}=713.56m$
