Setting the Stage
Malcolm Swordfish president of Ptomaine Fish Company needs help. He is looking to hire a delivery company for his business. But heís not sure which company to choose. So he writes a letter (see page 4) to your math class for some help. The teacher passes out the letter (and copies) to each group of 3 or 4 students. After reading the letter they will be asked to come up with advice for Mr. Swordfish.  The program they use is the function plotter component of Green Globs and Graphing Equations, but any graphing program (like Excel or Clarisworks) would work. The students need to help Mr. Swordfish decide among these delivery services:

• Pretty Good Delivery Co. charges a $15.00 monthly fee and $.25 for each delivery.
• Really Decent Delivery Co. charges an $8.00 monthly fee and $1.00 for each delivery.
• Unbelievably Great Delivery Co. waives the monthly fee and charges $3.00 for each delivery.

Doing the Activity

1. Using a spreadsheet make a table like this:

2. Make a chart for each company's per delivery costs. Analyze the graphs and decide on your answers.

Solutions and Debriefing

The students came up with three functions that represented the fee structure of the delivery companies and they graphed them on the same coordinate grid.  After they finished with their graphs, they went back to their table and prepared a presentation to Mr. Swordfish. All the groups eventually concluded that the Unbelievably Great Delivery Co. was best if you had just a few deliveries, the Really Decent Company was the best after about 4 deliveries and the Pretty Good Company was cheaper when you need more than 9 deliveries. So the answer to the question of which company was best was: it depends!