Consider this solution:
1) formula of volume is [tex]V= \frac{4}{3} \pi r^3, where \ r - radius[/tex]
2) if new_r=2r, then the formula is [tex]new_V= \frac{4}{3}*(2r)^3= \frac{4}{3} \pi *8r^3=8*( \frac{4}{3} \pi r^3)[/tex]
3) new_V/V=8:1
The volume increases by 8 times.
