At the surface of the Earth, g=9.8 m/s/s The further we go from the surface of the Earth, the smaller the affect of gravity has on objects at different heights.
You are looking for the height it takes to go from 9.8 m/s/s to 2.94. Which is 30% of 9.8.
The expression for
g is given by: gr =GM/R2 (that’s r squared)
The value of
g changes according to
(g)(h) = G x M /(R + h) 2 (again, this is squared)
To work this out on your calculator, take
( gh / gr) = (Rsquared /(R + h) squared
In this formula, R (radius since we are working with basically a sphere) can be used at h (height) so now we can simplify the equation
I hope this helps