Calculating the radius of a planet

[onie mti]

If you have an object that undergoes a free fall from on a planet Mars which experiences a gravitational acceleration of magnitude 3,8m/s(squared) the mass of mass is given to be 6,4*10^i23kg. Please how do I find the radius of mars

 

[I like Serena]

If you have an object that undergoes a free fall from on a planet Mars which experiences a gravitational acceleration of magnitude 3,8m/s(squared) the mass of mass is given to be 6,4*10^i23kg. Please how do I find the radius of mars

Apply the formula of gravity:
$$a=\frac{GM}{R^2}$$
where $a$ is the acceleration at the surface, $G$ is the gravitational constant ($6.67\cdot 10^{-11}$), $M$ is the mass of the planet, and $R$ is the radius of the planet.