Question

In the given figure, a cylindrical wrapper of flat tablets is shown. The radius of a tablet is 7 mm and its thickness is 5 mm. How many such tablets are wrapped in the wrapper?

Answer 1

Radius of a tablet, r = 7 mm

Thickness of a tablet, h = 5 mm

Radius of cylindrical wrapper, R = $\frac{14}{2}$ = 7 mm

Height of cylindrical wrapper, H = 10 cm = 100 mm (1 cm = 10 mm)

Let n be the number of tablets wrapped in the wrapper.

$$\begin{gathered} n=\frac{\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{cylindrical}\mathrm{wrapper}}{\mathrm{Volume}\mathrm{of}\mathrm{each}\mathrm{tablet}} \\ \Rightarrow n=\frac{\mathrm{\pi }{R}^{2}H}{\mathrm{\pi }{r}^{2}h} \\ \Rightarrow n=\frac{{\left(7\right)}^2\times 100}{{\left(7\right)}^2\times 5}=20 \end{gathered}$$
Thus, 20 tablets are wrapped in the wrapper.