Question

The number of coins of radius 0.75 cm and thickness 0.2cm required to be melted to make a right circular cylinder of height 8 cm and base radius 3 cm is :

Answer 1

in this case, the volume of cylinder formed by a number of coins is equal to the cylinder by melting it.
let n be the number of coins
n*πr^2h=πr^2h
n*0.75*0.75*0.2=3*3*8
n=8*8*10
n=640
That means number of coins are 640