A pipe is 2" outside diameter and it has 3/16" walls .What is the inside diameter,?

2 - 2(3/16)

2 - 6/16 = 1 10/16 = 1 5/8

Ido not know how you got the ansmwer could you please explain.

See your later post for an explanation.

To find the inside diameter of a pipe, you need to subtract the thickness of the walls from the outside diameter.

Given:
Outside diameter = 2"
Wall thickness = 3/16"

First, let's convert the wall thickness to inches:
3/16" = 0.1875"

Now, subtract the wall thickness from the outside diameter:
Inside diameter = Outside diameter - 2 * Wall thickness
Inside diameter = 2" - 2 * 0.1875"
Inside diameter = 2" - 0.375"
Inside diameter = 1.625"

Therefore, the inside diameter of the pipe is 1.625".