Question 878187
One would guess you want the volume of the balloon which has circumference 16 pi. units of cubic inches for the volume.


{{{2pi*r=16}}} and {{{v=(4/3)pi*r^3}}};
You want to solve for v.


From circumf, {{{r=16/(2pi)=8/pi}}}.


{{{highlight(v=(4/3)pi(8/pi)^3)}}}-------you take it from here.
(The rendering puts one of the {{{pi}}} into the wrong position.  That is not an exponent.  The raised "3" is an exponent, but the other raised number, {{{pi}}} is a FACTOR.)