Word Problem: Linear Function

Question

A speeding ticket is $100 plus $5 for every 1 mph over the speed limit.

a) Write a linear function to model the cost S(x) (in $) of a speeding ticket for a person caught driving x mph over the speed limit.

b) Evaluate S(15) and interpret the meaning in the context of this problem.

Answer 1

The slope of the line is the cost per speed.  Therefore, your linear function will be

 

S(x) = 5x + 100

 

 

S(15) means to evaluate S(x) at x=15.  This gives you the cost of driving 15 mph over the speed limit.