Answer: 11.8 ft
Step-by-step explanation:
Given
Volume of sphere [tex]V=6915\ ft^3[/tex]
Also, the volume of a sphere
[tex]\Rightarrow V=\dfrac{4}{3}\pi r^3[/tex]
Putting values
[tex]\Rightarrow V=6915=\dfrac{4}{3}\pi r^3\\\\\Rightarrow r^3=\dfrac{6915\times 3}{4\pi}\\\\\Rightarrow r^3=1650.1704\\\Rightarrow r=11.8\ ft[/tex]