A question on a test asks students to find the speed at which a car travels. The graph shows a proportional relationship between the distance traveled in miles and time in hours. incorrectly says that the speed of the car is 1/61 mile per hour. What is the speed of the car? What error might have made?

Since, speed of a car = distance traveled/time taken

From  the graph attached,

A point (1, 60) lies on the line shown in graph.

At this point speed of the car =  

                                               = 60 miles per hour

But Billy says the speed of the car is 1/60 miles per hour.

So the error in the Billy's answer is that he has used the wrong formula to calculate the speed.

(As per Billy, speed = )

Step-by-step explanation:

11) obtuse

13)right

15) acute