The rectangular tank, 10 ft high by 20 ft wide by 40 ft long, is to be completely painted inside with two coats. Each gallon covers 50 sq. ft. How many gallons of paint are required?

To determine how many gallons of paint are required, we first need to calculate the total surface area of the inside of the tank that needs to be painted. The dimensions of the tank are 10 ft high, 20 ft wide, and 40 ft long.

The inside surface area of a rectangular tank can be calculated by finding the area of each of its faces:

1. Two side walls: Each side wall has an area of height multiplied by length:

• Area = height × length = 10 ft × 40 ft = 400 sq. ft.

• Since there are two side walls, the total area for the side walls is 2 × 400 sq. ft. = 800 sq. ft.

2. Two end walls: Each end wall has an area of height multiplied by width:

• Area = height × width = 10 ft × 20 ft = 200 sq. ft.

• Since there are two end walls, the total area for the end walls is 2 × 200 sq. ft. = 400 sq. ft.

3. Bottom of the tank: The bottom has an area of width multiplied by length:

• Area = width