Find the weight used to construct the pool

Question

The inner dimensions of an in-ground swimming pool are: width = 13.0 ft, length = 18.0 ft, and depth = 9.0 ft. The pool walls and the bottom are uniformly 1.0 ft thick and made of concrete. What is the weight, W (in pounds) of the concrete used to construct the pool, if one cubic inch of concrete weighs 0.25 pounds?

I'm completely stumped.

Answer 1

Volime of bottom:

15' x 20' x 1'= 300 ft³, additional 2 feet on all sided for footings under the walls

Two pairs of wall have similar additions of 2 feet to share with the other walls.

Volume of pair with added feet

2 x 20' x 9' x 1'= 360 ft³

Voume of pair with the subtraced feet

2 x 11' x 9' x 1'= 198 ft³

858 ft³

Can you convert to cubic inches, calculate cost, and answer?

Answer 2

Find the volume of the pool walls.

Volume of width = 2 x 13 x 1 x 9 = 234 ft³

Volume of Length = 2 x 20 x 1 x 9 = 360 ft³

Add volumes for total volume = 234 + 360 = 594 ft³

Convert to cubic inches = 594 ft³ x (1728 in³/ft³) = 1026432 in³

Find weight

W = (0.25 lb / in³) x (1026432 in³) = 256608 lb <-- Solution