Given that the acceleration of gravity at the surface of mars is 0.38 of what it is on earth, and that mars' radius is 3400 km, determine the mass of mars. show me how to do !

The equation that is applicable is as follows:
F = G * M * m ÷ r^2 F = G * M * m ÷ r^2 
Weight = m * g 
Weight = F m * g = G * M * m ÷ r^2 g = G * M ÷ r^2 
Now you can determine the mass of the planet. For mars, r = 3,400,000 = 3.4 * 10^6 meters 
0.38 = 6.67 * 10^-11 * M ÷ (3.4 * 10^6)^2 0.38 = 6.67 * 10^-11 * M ÷ 1.156 * 10^13 
3.8 = 6.67 * 10^-11 * M ÷ (3.4 * 10^6)^2 0.38 = 6.67 * 10^-11 * M ÷ 1.156 * 10^13 Multiply both sides by 1.156 * 10^13 
1.156 * 10^13 * 0.38 = 6.67 * 10^-11 * M Divide both sides by 6.67 * 10^-11 
1.156 * 10^13 * 0.38 ÷ 6.67 * 10^-11 = M The answer is approximately 6.586 * 10^22 kg The actual mass of Mars is 6.42 * 10^23 kg. I think the acceleration of gravity on Mars is 3.8 m/s^2 
1.156 * 10^13 * 3.8 ÷ 6.67 * 10^-11 = M The answer is approximately 6.586 * 10^23 kg

Ibelieve the answer is b

Ibelieve that the correct answer is: c. along plate boundaries