one fine day in the city

Comparing Cell Phone Plans

AT&T Wireless Cell Phone Plans
The cost for a cell phone varies from company to company and plan to plan within each company. A plan that suits one person may not be beneficial to another. Explore the pricing and the rate of change in each of the following single-line plans from AT&T.
Plan with 450 minutes
Plan with 900 minutes
Plan with unlimited minutes
Use the Plan Description to complete the tables (see the example below) and to plot the data points on the grid to the right of each table. Connect the points with appropriate line(s).
Example: A plan with 300 minutes
Plan Description: $5.99 per month with 300 minutes; additional fee of $.05 for each minute over the 300 limit
To create ordered pairs to graph the relationship, cost was calculated for minutes in increments of 200, beginning with zero. The values in the Total Cost column are calculated based on the Plan Description.
# of Minutes
Total Cost
Calculations
0
$5.99
Monthly charge
200
$5.99
Monthly charge (200 of the first 300 minutes of the plan)
400
$10.99
Monthly charge (includes first 300 minutes), plus remaining 100 minutes at .05/minute = $5.00.
600
$20.99
Monthly charge (includes first 300 minutes), plus remaining 300 minutes at .05/minute = $15.00.
800
$30.99
Monthly charge (includes first 300 minutes), plus remaining 500 minutes at .05/minute = $25.00.
1000
$40.99
Monthly charge (includes first 300 minutes), plus remaining 700 minutes at .05/minute = $35.00.

Plan A – Plan with 450 Minutes Plan Description: $39.99 per month with 450 minutes then $0.45 per minute for additional minutes.

Minutes used in a month
Total Cost (dollars)
0
39.99
150
39.99
300
39.99
450
39.99
600
107.49
750
174.99
900
242.49
1050
309.99
1200
377.49

Plan B – Plan with 900 Minutes

Plan Description: $59.99 per month with 900 minutes then $0.40 per minute for additional minutes.

Minutes used in a month
Total