Question

The following data table represents the total cost of a monthly cell phone bill as a function of the number of minutes that the phone is used each month.

Minutes 500 750 1,000 1,250 1,500
Total Monthly Cost (in dollars) $62 $77 $92 $107 $122
The table shows that as more minutes are used each month, the total monthly cost will increase at the same rate. Assuming that this is true, what is the total monthly cost for the cell phone if it is used for 2,500 minutes?


WRITER

Answer 1

First find the rate: between 500 and 750 minutes the cost rises by $15 for 250 minutes, so rate = 15/250 = $0.06 per minute.

From 500 to 2500 minutes is 2000 extra minutes, so extra cost = 2000 × 0.06 = $120.

Total cost = $62 + $120 = $182.