A solid is in the form of a cylinder with hemispherical ends. The total height of the solid is $\displaystyle 20$ cm and the diameter of the cylinder is $\displaystyle 7$ cm. Find the total volume of the solid. (Use $\displaystyle \pi=\frac{22}{7}$ )

Radius of cylinder = radius of hemisphere $\displaystyle =\frac{7}{2} \mathrm{~cm}$ Total height of solid $\displaystyle =20 \mathrm{~cm}$ \[\begin{array}{l} \text { Height of cylinder }=\left(20-\frac{7}{2}-\frac{7}{2}\right) \mathrm{cm}=13 \mathrm{~cm} \\ \begin{aligned} \text { Total volume of solid } & =\left[\frac{22}{7} \times\left(\frac{7}{2}\right)^{2} \times 13+2 \times \frac{2}{3} \times \frac{22}{7} \times\left(\frac{7}{2}\right)^{3}\right] \\ & =\frac{22}{7} \times\left(\frac{7}{2}\right)^{2} \times\left(13+\frac{14}{3}\right) \\ & =\frac{4081}{6}=680.1 \mathrm{~cm}^{3} \text { (approx.) } \end{aligned} \end{array} \]