Surface Area of a Cylinder (read description)

Question

Latisha has 50 coins. Each coin has a diameter of 1.5 cm and is 0.2 cm thick. She piles them up to form a cylinder. What is the total surface area of a cylinder that could be made as a closed container for his coins?

Answer 1

Since the thickness of each coin represents part of the height of the cylinder, then the 50 times the coin thickness is the height of the cylinder.

 

h = 50 * 0.2 cm

h = 10 cm

 

 

Radius is half the diameter.

 

r = 1.5 cm / 2

r = 0.75 cm

 

 

Use the formula for surface area of a cylinder.

 

SA = 2πr² + 2πrh

 

 

Now plug in the value of r and h into this formula.