PBL Pathways

Content Area

College Algebra, Precalculus, Calculus

Time Frame

2 to 3 weeks


Sept. 10, 2008


Regression modeling, polynomials, rational functions, limits

Project Title

Cell Phones


David Graser, Yavapai College, Prescott, AZ (David_Graser@yc.edu)


This project involves modeling the revenue per cell phone subscriber based on data for the number of cell phone subscribers and the total revenue from those subscribers. There are many different ways you could model this data. For instance, you could divide the revenue by the subscribers for each year and model the resulting quotients. Unfortunately, modeling this quotient with a polynomial leads to a function that grows or decays as x approaches infinity. Realistically, you would expect the revenue per subscriber to level off. A strategy is outlined for the student to model the subscribers with a polynomial and the revenue with another polynomial. Then the revenue per subscriber is modeled by a rational function formed from the two polynomials.

Project Content

Project Letter: DOC | PDF

Scaffolding Resources




Contact Me | ©2008-2013 PBL Pathways PBL Logo | Copyright Statement