1. The problem statement, all variables and given/known data The problem is stated in the picture. 2. Relevant equations Fg=Gm.1m.2/r^2 3. The attempt at a solution I found a similar question where someone wanted to find how high will the weight be half the weight on the surface. Here is one of the answers: F =G.m1.m2/r^2 F´ =G.m1.m2/r´^2 so F/F´= r´^2/r^2 = (r´/r)^2. So I tried applying it to my situation. I wrote 34/100=r'^2/(6.38*10^6)^2. Solving for r' I got an answer of x=3.72*10^6meters=3720km. The correct answer of 4600km is displayed in the screen shot attached. I really don't understand how to do these problems, though I do understand that Fg is inverse square proportional to r. Any help would be greatly appreciated. Thanks.