we know that
volume of a sphere=(4/3)*pi*r³
in this problem
circumference=26 m
circumference=2*pi*r
so
26=2*pi*r----------> r=26/(2*pi)----> 4.14 m
volume of a sphere=(4/3)*pi*(4.14)³---> 297.08 m³------> 297.1 m³
the answer is
volume of a sphere is equal to 297.10 m³
