  ### Home > MC2 > Chapter 9 > Lesson 9.3.1 > Problem9-84

9-84.

Use the graph at right to answer the following questions.

1. What is this graph describing? Write an appropriate title for the graph.

Look at the $x$-axis and $y$-axis labels. The graph shows the
distance from home at several different time periods.

Possible title: Distance and Time

2. How far from home is the person when the graph starts?

The graph starts at 0 hours. Which means this person just
started the travel. What is the distance from home at $0$ hours?

He starts at $9$ miles from home.

3. How fast is the person traveling? Explain how you can use the graph to determine the rate of travel.

Find the slope of the line.

${\text{Find the } \frac{\text{rise}}{\text{run}}}$

${\frac{10}{4} = 2.5 \text{ miles per hour}}$ 4. Write an equation to represent the line on the graph.

A slope of $2.5$ means that the distance from home increases $2.5$ miles per hour. That means we multiply $2.5$ and any hour which we will call $x$.

Since we know how fast this person is traveling, we also need to know the starting distance. From part (b) we found that this person started $9$ miles away from home.  