Question

A water pipe has an outside diameter of 1 1/4 inches and a wall thickness of 5/16 inches. what is the inside diameter of the pipe?

Answer 1

Explanation:

There's a small trick here. You have to double the thickness. Why? Because the outside diameter goes through the thickness twice.

Inside diameter = outside diameter - 2 * thickness

outside diameter = 1 1/4 inches

thickness = 5/16

Inside diameter = 1 1/4 - 2 * 5/16

inside diameter = 5/4 - 10/16

Inside diameter = 5/4 - 5/8

Inside diameter = 10/8 - 5/8

Inside diameter = 5/8