(a) The value of acceleration due to gravity $g$ at height $h$ above the surface of earth is
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ g_{h} = \frac{g}{\left( 1 + \frac{h}{R} \right)^{2}}$
Where $R$ is radius of earth.
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \frac{g}{g_{h}} = \left( 1 + \frac{h}{R} \right)^{2}$