[kapilbajaj]

Find the number of coins 0.8 cm in a radius and 0.4 cm thick to be melted to form a right circular cylinder of height 10 cm and 8 cm as radius

[momosur]

Volume of coin = 3.142(pi or 22/7) * 0.8 * 0.4 = V1

Volume of cylinder = 3.142(pi or 22/7) * 10 * 8

No. of coins required = (10 * 8 * pi) / (0.8 * 0.4 * pi)

{pi and pi get cancelled}

Therefore, coins = 10*8/.8*.4
= 80/.32
= 250
------

Problem solved! :)

[jcaron2]

Sorry, Momosur, but that is NOT the formula for the volume of a cylinder. You need to use the square of the radius.

Nevertheless, Kapilbajaj, Momosur showed you exactly how to solve the problem (other than needing to square the radius for both volume calculations). So what do you get when you work out the problem correctly?

[momosur]

Oops. Sorry about that
Slipped out of my mind :p

thanks for correcting my mistake :)

correct answer is 250 * 8 / 0.8 = 2500

:)

[jcaron2]

I figured you probably knew that. Just a simple oversight. I do it all the time. :)