A vessel is in the form of an inverted cone. Its height is 8 cm and the radius of its top, which is open,
A vessel is in the form of an inverted cone. Its height is 8 cm and the radius of its top, which is open, is 5 cm. It is filled with water upto the brim. When lead shots, each of which is a sphere of radius 0.5 cm are dropped into the vessel, one fourth of the water flows out. Find the number of lead shots dropped in the vessel.
Height of the conical vessel (h) = 8 cm
Base radius (r) = 5 cm
Volume of water in conical vessel $=\frac{\mathbf{1}}{\mathbf{3}} \pi \mathrm{r}^{2} \mathrm{~h}$
$=\frac{1}{3} \times \frac{22}{7} \times(5)^{2} \times 8 \mathrm{~cm}^{3}$
$=\frac{\mathbf{4 4 0 0}}{\mathbf{2 1}} \mathrm{cm}^{3}$
Now, Total volume of lead shots
$=\frac{1}{4} \times \frac{4100}{21} \mathrm{~cm}^{3}=\frac{1100}{21} \mathrm{~cm}^{3}$
Since, radius of spherical lead shot $(\mathrm{r})=0.5 \mathrm{~cm}$
$\therefore$ Volume of 1 lead shot $=\frac{\mathbf{4}}{\mathbf{3}} \pi \mathrm{r}^{3}$
$=\frac{4}{3} \times \frac{22}{7} \times \frac{5}{10} \times \frac{5}{10} \times \frac{5}{10} \mathrm{~cm}^{3}$
$\therefore$ Number of lead shots
$=\frac{\text { Total volume of lead shots }}{\text { Vohme of } 1 \text { lead shot }}=\frac{\left[\frac{1100}{21}\right]}{\left[\frac{4 \times 22 \times 5 \times 5 \times 5}{3 \times 7 \times 1000}\right]}$
= 100
Thus, the required number of lead shots = 100.