Question

Plastic drum of a cylindrical shape is made by melting spherical solid plastic balls of radius 1 cm.
Find the numbers of balls required to make a drum of thickness 2 cm and height 90 cm, outer
radius is 30 cm.
(Diagunel)
leva ?​

Answer 1

Answer: 270

Step-by-step explanation:

Since the drum is made by melting spherical balls, the combined volume of the balls will equal the volume of the drum (a cylinder)

Lets assume that n number of balls are required

n X $\frac{4}{3}\pi r^{3}$ = $\pi r^{2} h$

Since the drum is hollow, instead of the radius r, the thickness should be considered for calculating the volume, hence,

n X $\frac{4}{3}\pi r^{3}$ = $\pi t^{2} h$

n X $\frac{4}{3} X \pi X 1^{3}$ = $\pi X 2^{2} X 90$

n X $\frac{88}{21}$ = $\frac{7920}{7}$

n = $\frac{7920}{7}$ X $\frac{21}{88}$ =

n = 270