Question

To function properly, a rainwater outflow pipe must drop exactly 1 inch for every 25 inches of horizontal distance. A 40 feet long rainwater pipe runs under the edge of a roof. What is the vertical distance, in inches, the pipe must drop between its ends? Round your answer to the nearest tenth.

Answer 1

1 inch drop for every 25 inches length
40 feet= 12 x 40 = 480 inches
There are 19.2-25 inch lengths in 480 inches.
So there is a  19.2 inch drop  in 40 feet. 

Hope this helps :)