Question

(01.07 mc)
a driver takes a trip away from home. this person’s position during the five-hour drive is plotted on the graph below. the starting position (0, 0) is the driver’s home.
graph: position vs. time (x-axis: time (hours), y-axis: position (miles))
if it took the driver three hours to come home. calculate the average speed of the car for the return trip home.
options:
○ a 3 miles/hour
○ b 20 miles/hour
○ c 25 miles/hour
○ d 75 miles/hour

Explanation:

Step1: Determine the distance for return trip

From the graph, the maximum position (distance from home) is 75 miles (since the last point is at 75 miles). So the distance for the return trip is 75 miles (as they come back home, distance is from 75 miles to 0 miles, so total distance is 75 miles).

Step2: Use the average speed formula

The formula for average speed is $v = \frac{d}{t}$, where $d$ is distance and $t$ is time. Here, $d = 75$ miles and $t = 3$ hours.
So, $v=\frac{75}{3}=25$ miles/hour.

Answer:

c. 25 miles/hour