Building a
Step Function
  1. Ceiling
  2. Greatest Integer
  3. Graphing
  4. Modeling









Domestic Rates
Data

   ATT True Reach Savings
   MCI Basic Residential
   LCI All America Plan








 
Modeling Phone Data
Phone companies will determine the price of a call by rounding the length of the call to a certain time period (either one minute or six seconds). For instance, a local weekday call on MCI's Basic Residential plan will cost $0.2599 each minute.

How much would a 5.2 minute call cost?

Solution

Questions

Answer the following questions using the Domestic Rates Data locations shown to the left. Round each answer to TWO DECIMAL PLACES. SHOW YOUR WORK on a separate sheet of paper. Press TAB after answering each question on the screen.

1.What is the cost of a 10.2 minute, evening, 38 mile call on ATTs True Reach Savings?ANSWER = $
2.Find the price for this month's phone bill that contains one 28.4 minute, 208 mile, Sunday evening call on MCIs Basic Residential plan. Don't forget the national service fee!ANSWER = $
3.Find the ceiling function that will determine the price of a phone bill containing one Sunday evening call on MCIs Basic Residential plan. Let t represent the length of the phone call. Graph the function and verify your answer to question 2 using one of the following methods (depending on your technology):
  1. Java Function Grapher from Cognologic Software: Click on the icon to the left. Let x(t)=t, set the window from t = 25 to t = 30, DO NOT check aspect ratio, and use ceil(t) to represent the ceiling function in y(t).
    Note: The function will not appear discrete due to a small bug in the program.
  2. Graphing calculator
  3. Geometer's SketchPad file: Click on the compass icon to the left. (Directions for Dowload).
YOUR INPUT TO THE RIGHT SHOULD CONTAIN ceil(t) AND NOT CONTAIN ANY SPACING.
C(t) =
4.Find the price of a Wednesday call from 6:36 AM (and 12 seconds) until 6:45 AM (and 32 seconds) using LCIs All American PlanANSWER = $

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