Given data:
The mass of planet is M.
The radius of planet is R.
The initial velocity of projectile is v₀=0.762ve.
The amount of kinetic and potential energy should be equal according to conservation of energy,
[tex]\begin{gathered} KE=PE \\ \frac{1}{2}mv^2_e=\frac{GMm}{R}^{}_{} \\ R=\frac{GM^{}_{}}{v^2_e} \end{gathered}[/tex]The escape velocity is given by,
[tex]v_e=\sqrt[]{\frac{2GR}{M}}[/tex]Here, G is the universal gravitational acceleration.
The time taken to reach the maximum height will be,
[tex]\begin{gathered} v_0=gt \\ t=\frac{v_0}{g} \end{gathered}[/tex]The maximum height reached by the projectile is given by,
[tex]\begin{gathered} h=v_0t+\frac{1}{2}gt^2 \\ h=v_0(\frac{v_0}{g})+\frac{1}{2}g(\frac{v_0}{g})^2 \\ h=\frac{v^2_0}{g}_{}+\frac{1}{2}\frac{v^2_0}{g}_{} \\ h=\frac{3}{2}\frac{v^2_0}{g}_{} \\ h=\frac{3}{2}R \\ \frac{h}{R}=1.5 \end{gathered}[/tex]