finding the radius and diameter

Question

A circular pipe has an inside radius of 10.6 cm and a wall thickness of 2.575 cm. It is surrounded by insulation having a thickness of 4.4 cm.

 

What is the outside diameter of the insulation?

Retain the proper number of digits in your answer.

Answer 1

Add the radius, the wall thickness, and the thickness of the insulation:

 

10.6 cm + 2.575 cm + 4.4 cm = 17.575 cm

 

The diameter is twice the radius, therefore double the number:

2 x 17.575 = 35.15 cm

 

Now round it because you can only have one digit after the decimal point:

35.2 cm