A transportation company will carry specialty deliveries for a distance of 1200 miles. The cost for the first 600 miles is $3.75 per mile and then $0.85 per mile after that.
Which of the following graphs most accurately shows the relationship between the cost of transportation and total mileage?

Question

Quizplus · Accepted Answer

A transportation company will carry specialty deliveries for a distance of 1200 miles. The cost for the first 600 miles is $3.75 per mile and then $0.85 per mile after that. 
The price per mile starts at $3.75 per mile for the first 600 miles. This means that for each added mile, the price increases at a constant rate of $3.75. Because the increase is constant with each mile, the graph should be linear before 600 miles with a slope of 3.75. 
After 600 miles, the rate slows to $0.85 per mile. This means the slope of the line will decrease and become shallower. For each mile added after 600 miles, $0.85 will be added to the total cost. The rate of increase is still constant, it is just increasing at a different constant rate. 
A graph that matches these conditions would be linear both before and after 600, with a bend at 600. The line after 600 will have a shallower slope than the line before. The only graph that satisfies these requirements is the one above.

A Transportation Company Will Carry Specialty Deliveries for a Distance