Question

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

Answer 1

for coin

d=1.5cm

r=1.5/2cm

h=0.2cm

for cylinder

R=4.5/2cm

H=10cm

Number of coins=

Volume of cylinder/

Volume of coin

=pi Rsquare H/pi r square h

=(4.5/2)square 10/

(1.5/2)square 0.2

=50.625/0.1125

=450

450 coins can be made.