radius = diameter/2
radius = 6.5/2 = [tex] \frac{13}{4} [/tex]m
volume [tex]= \frac{4}{3} [/tex] x [tex] \pi [/tex] x (radius)³
[tex]= \frac{4}{3}[/tex] x [tex] \pi [/tex] x [tex]( \frac{13}{4})^3[/tex]
[tex]= \frac{4}{3} [/tex] x [tex] \pi [/tex] x [tex] \frac{2197}{64}[/tex]
[tex]= \frac{2197}{64} [/tex]
= 144 cubic meters