Answer:
0.196 lbs
Step-by-step explanation:
The area of the cross section is the difference of the areas of circles with the different diameters. The volume of the pipe material is the product of its cross section area and its length:
V = π(D² -d²)L/4 = π(0.82² -0.75²)36/4 ≈ 3.107 . . . in³
Then the weight of the material is this volume multiplied by the density.
W = V·δ = (3.107 in³)(0.063 lb/in³) ≈ 0.196 lb
