Example 4.39 from Elementary Algebra, 4.4 Understand Slope of a Line

Understand Slope of a Line: example 4.39

Have you ever thought about the sewage pipes going from your house to the street? They must slope down $\frac{1}{4}$ inch per foot in order to drain properly. What is the required slope?

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution

Use the slope formula. $\begin{matrix} m = \frac{rise}{run} \\ m = \frac{- \frac{1}{4} inch}{1 foot} \\ m = \frac{- \frac{1}{4} inch}{12 inches} \end{matrix}$

Simplify. $m = - \frac{1}{48}$

The slope of the pipe is $- \frac{1}{48}$ .

The pipe drops 1 inch for every 48 inches of horizontal run.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Find the slope of a pipe that slopes down $\frac{1}{3}$ inch per foot.

How did it go?

Use the slope formula.	$\begin{matrix} m = \frac{rise}{run} \\ m = \frac{- \frac{1}{4} inch}{1 foot} \\ m = \frac{- \frac{1}{4} inch}{12 inches} \end{matrix}$
Simplify.	$m = - \frac{1}{48}$
	The slope of the pipe is $- \frac{1}{48}$ .

Solution

Your turn

Solution

Your turn