the moon takes 27.3 days (2.36x10^6s) to orbit the earth . Calculate its distance from the earth . Take the mass of the earth to be 5.975x10^24kg.

Use the set formula T²=(4Pi^2/GM)R^3 and rearrange for r^3 to give
r³= T²GM/ 4Pi²
then insert values : r³ = (2.36x10⁶)² x 6.67x10^-11x 5.975x10²⁴/ 4PI² = 5.62....x10²⁵
Then take the cube root of R³ to give 3.830....x10⁸. Question is in 3 sig fig so also give answer in 3 sig fig- so r= 3.83x10⁸m (to 3 s.f) - which is the distance between the centre of the Earth and the centre of the Moon.