10 km
First step: Divide 523.6 by 4/3
Second step: You'll get 392.7 from step one and you'll divide that by Pi.
Third step: you take the cube root of the number that you get from the second step and you'll get 125.
And you end up with 5 km, but it's the diameter so you must multiply by 2
Final answer: 10 km