A hemispherical metal bowl has internal radius 5 cm and external radius 6 cm. Find the volume of metal used to make it, in cubic centimetres, correct to two decimals. (Take π = 3.14.)

The metal is the outer hemisphere minus the hollow inner hemisphere: $\frac{2}{3}\pi (R^3-r^3)=\frac{2}{3}(3.14)(216-125)=\frac{2}{3}(3.14)(91)=190.49{\text{cm}}^3$. 380.99 uses $\frac{4}{3}$ instead of $\frac{2}{3}$, i.e. treats each shell as a full sphere; 452.16 is the outer hemisphere alone with nothing hollowed out; 2.09 comes from cubing the difference of the radii, $(R-r{)}^3=1$, instead of taking the difference of the cubes.