If the radius of a sphere is doubled, what is the ratio of the volume of the first sphere to that of the second sphere?

Explanation

Let the original radius be `r`
so the original volume `=4/3pir^3`
New Radius `=2r`
So the new volume `=4/3pi(2r)^3=4/3pixx8r^3`
Ration`=(4/3pir^3)/(4/3pixx8r^3)=1/8`
so ratio `= 1:8`