14. The monthly cost of driving a car depends on the number of miles driven. Lynn found that in May it cost her $380 to drive 480 mi and in June it cost her $460 to drive 800 mi.

Question

a) Express the monthly cost C as a function of the distance driven d, assuming that a linear relationship gives a suitable model.
b) Use part (a) to predict the cost of driving 1500 miles per month.
c) Draw the graph of the linear function. What does the slope represent?
d) What does the y-intercept represent?
e) Why does a linear function give a suitable model in this situation?

Answer 1

I assume you know how to handle equations of a straight line of the form y = mx + b if you are given two ordered pairs of the form (x,y)

So interpret your data as two ordered pairs of the form (m,c), m for miles c for cost.
so you would have (480,380) and (800,460)

so proceed by finding the slope etc
just like you would for the more familiar points.

the rest of the questions are of a type very common for the y = mx + b notation.