Question

the radius and height of a metallic cylinder are 4.2 cm and 5.6 cm respectively. it is melted and recast into a sphere. find the radius of the sphere

Answer 1

$$\begin{gathered} \mathrm{After}\mathrm{recast}, \\ \mathrm{Volume}\mathrm{of}\mathrm{cylinder}=\mathrm{volume}\mathrm{of}\mathrm{sphere} \\ {\mathrm{\pi r}}^2\mathrm{h}=\frac{4}{3}{\mathrm{\pi r}}^3 \\ 4.2\times 4.2\times 5.6=\frac{4}{3}\times {\mathrm{r}}^3 \\ {\mathrm{r}}^3=74.08 \\ \mathrm{r}=4.19\mathrm{cm} \end{gathered}$$