comparisons and operations
Comparing costs: internet providers

Over the last years more and more people are connecting to the Internet using a personal computer and a modem. Some people connect for only a few minutes a day, to send and receive e-mail. Others connect for several hours a day to surf the net. Businesses and institutions need to be connected to the Internet all the time.
To connect to the Internet one must sign-up with an Internet Service Provider (ISP). ISPs use different ways to charge their fees. In the following task examine two such fee structures, proposed by two competing ISPs. Investigate the consequences of changing the fees to help a company plan a fee reduction that will attract new customers.


Compare the fees charged by two ISPs. Each one charges a daily fee based on the amount of time the user is connected to the Internet.
daily fee (dollars)
daily hours of usage
The InterLine company charges a fixed daily fee of 30 cents. On days on which the user does not connect to the Internet, no fee is charged. In addition, the company charges 14 cents per hour of connection.

The Parabolic company does not charge a fixed daily fee. Payment for the first hour of usage is 24 cents, for the second hour 23 cents, for the third hour 22 cents, and so on. The following correspondence rule describes the dependence of Parabolic's daily charges (in dollars), on the number of hours of usage:
f(x)=x(49-x)/200.

The two companies are competing for customers, and one of them wants to reduce its fee to draw customers away from its competitor.
Here are some proposed methods of cost reduction:

Reducing daily charges by a fixed amount (for example: "80 cents off each day").
  • Offering some free time every day (for example: if the free time is 30 minutes, users connecting for 2 hours will as if they had been connected for 1.5 hours).
  • Reducing the clock rate (for example: if the clock rate is reduced by a factor of 2, users connecting for one hour will pay as if they had been connected for 30 minutes).
  • Offering a discount of a certain percentage (for example: reducing the fee by 20%).
  • Offering a reduction of the daily fee depending on how long users are connected (for example: 5 cents off the first hour, 10 cents off the second hour, etc.).


  • One of the ISPs is soliciting your advice

    Advise the ISP how to reduce fees in order to draw away customers from its competitor. Prepare a report and present several proposals for changing the fees.
    Describe the current situation, before the fee reduction: which customers will prefer each of the ISPs?
  • Present several examples for changing the fees of the company you are advising. Explain your proposal in words as well as in the mathematical terms of "changing a function."
  • Explain why your proposals will attract customers away from the competing company.
  • Discuss the advantages and disadvantages of your proposal. Is there one proposal that you prefer over the others?
  • Consider the possibility that the competing ISP will imitate your method and offer a reduction of the same type as the one you proposed for your client. What will the situation be in this case?







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    Internet providers