# Math Help - conversion of units

1. ## conversion of units

The information on a one-gallon paint can is that the coverage, when properly applied, is 450 square ft. One gallon is 231 cubic inches. What is the average thickness of the paint in such an application?

can someone explain how to do this. I know that 450 sq. feet = 64800 square inches, but I don't know where to go from there.

the answer is: 0.0036 inches

2. $64800d = 231$ where d is the paint thickness.

3. Originally Posted by algebra2
The information on a one-gallon paint can is that the coverage, when properly applied, is 450 square ft. One gallon is 231 cubic inches. What is the average thickness of the paint in such an application?

can someone explain how to do this. I know that 450 sq. feet = 64800 square inches, but I don't know where to go from there.

the answer is: 0.0036 inches
View the paint as a rectangular solid. We know that the area of one of the large side is 64800 square inches. And we know that V = Ah, where h is the thickness you are looking for. So
$h = \frac{V}{A} = \frac{231~cu.in}{64800~sq.in} \approx 0.0036~in$

-Dan