# PBL Pathways

College Algebra

##### Time Frame

2 Weeks with Mini Lectures

April 1, 2008

##### Keywords

point-slope form, line, slope, data, linear, rate

College Costs

#### Author

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

#### Abstract

This project originated from an extensive data set of college costs published by the College Board. I needed a first project for my college algebra class that incorporated the concepts surrounding a linear equation and slope. Although this project could be done with almost any type of technology, I required my students to use Excel as well as Mathtype to help them document their work. In this project, each student was given a state for which the average college cost in 2004-2005 and 2007-2008 was known for two year colleges, public four year colleges and private four year colleges. For each type of institution, the student finds the equation of a line through the two data points and predicts when the college costs will double.

#### Project Content

Project Letter: DOC | PDF
Project Data: EXCEL | PDF

#### Scaffolding Resources

Technology Assignment 1: DOC | PDF - This assignment is designed to get the students graphing their data points on their graphing calculator and in Excel.

Technology Assignment 2: DOC | PDF - In this assignment, students will solve an equation algebraically and graphically. This should prepare them determining when their college costs have doubled.

How to Find a Point of Intersection on a TI Graphing Calculator PDF - This document shows how to put in two equations and find the point of intersection using the intersect command from the CALC menu.

How to Find a Point of Intersection in Excel PDF - This document shows how to find the point of intersection using GOAL SEEK in Excel.

#### Notes

Some states have institutions whose average costs are decreasing. If you choose to have your students find when costs double, don't choose one of those states.

Some possible options:

• The second worksheet in the Excel file has the annual data for college costs from 2004 to 2008. You could make this into a modeling project or find the equation of a line through a different set of years.
• Students could compare one type of institution in two different states.