Here's a boiled-down version of a question from Carnegie Mellon's Lifetime Math program:
Your boss tells you to find the best deal in cellular-phone service.
Economy service is $19.95 a month plus 31 cents per minute of airtime. Silver service is $40.95 a month plus 16 cents per minute of airtime. Gold service is $80.95 a month with free airtime.
Define variables. Write equations. Make tables and graphs. Find slopes and points of intersection. For each plan, how much airtime will $100 buy? For what range of airtime is each plan cheapest?
Updated June 14, 1997 by bwwebmaster
Copyright 1996, Bloomberg L.P.