Question

Ervin sells vintage cars. Every three months, he manages to sell 13 cars. Assuming he sells cars at a constant rate, what is the slope of the line that represents this relationship if time in months is along the x-axis and the number of cars sold is along the y-axis?

Answer 1

Ervin sells 13 cars per 3 months so 13/3=4.3 cars per month. 

this means that 

___month___     ___cars sold___

          1                         4.3
          2                     2*4.3
          3                     3*4.3
          :                           :
          n                     n*4.3

the linear function representing the cars sold per month is f(n)=4.3*n

(Practically, this means that the expected number of cars sold after n months is a whole number close to 4.3*n.)

Answer:

the slope is 4.3 (13/3)