For a cylinder
[tex]V_\textrm{cyl} = \pi r^2 h[/tex]
Since [tex]h = 2r[/tex]
[tex]V_\textrm{cyl} = 2 \pi r^3 [/tex]
We know that's 64 cubic meters,
[tex] 64 = 2 \pi r^3[/tex]
The sphere's volume is
[tex]V = \frac 4 3 \pi r^3 = \frac 2 3 (2\pi r^3) = \frac 2 3 (64) = \dfrac{128}{3}[/tex]
Answer: 128/3 cubic meters
That may be that choice peeking out at the bottom; can't really tell
