Question

find the number of coins, 1.5 cm diameter and 0.2 cm thick,to be melted to form a right circular cylinder with a height of 10 cm and a diameter of 4.5 cm.

Answer 1

let n is the number of coins
according to question
volume of cylinder =volume of n coins
pi.R^2H=n x pi.r^2.h
R^2.H=n.r^2.h
n=R^2H/r^2.h
now put H=10cm
R=4.5/2 cm
r=1.5cm
h=0.2cm
hence no of coins =450

Answer 2

Answer:

let n is the number of coins

according to question

volume of cylinder =volume of n coins

pi.R^2H=n x pi.r^2.h

R^2.H=n.r^2.h

n=R^2H/r^2.h

now put H=10cm

R=4.5/2 cm

r=1.5cm

h=0.2cm

hence no of coins =450