## One fine day in the city

Description: \$69. 99 per month with unlimited minutes and no charge for 69. 99 1 . Compare your graphs for Plan A, Plan B, and Plan C. Give a verbal description for each graph including what trend you notice and why that trend exists. Plan A has a horizontal line representing a constant cost no matter how many minutes are used until you reach 450 minutes. After 450 minutes, the line is oblique representing the cost increases as you use more minutes. Plan a: minutes are used until you reach 900 minutes. After 900 minutes, the line is oblique

Plan C: Plan C has a horizontal line representing a constant cost no matter how many minutes are used. 2. Calculate the rate of change in price for each plan. Plan A: 450 minutes included Rate of Change 67. 50 Plan B: 900 minutes included Plan C: Unlimited minutes a. For plan A, after the first 450 minutes, the rate of change in the total cost is 0. 45 dollars per minute. B. For plan B, after the first 900 minutes, the rate of change in the total cost is _0. 40 dollars per minute. C. For plan C, as the number of minutes increase, the rate of change in the _total cost remains the same at d.

What plan has the greatest increase in price as you use more minutes? Plan A has the greatest rate of change at 67. 50 dollars per 150 minutes which reduces to \$0. 45 per minute. 3. Using the data and your graphs, write an equation to describe the relationship between the number of minutes and the cost for each plan. Note for Plan A: write one equation only for the total cost for 450 minutes and higher. Note for Plan B: write one equation only for the total cost for 900 minutes and higher. Plan A: Let c = cost in dollars Let m = number of minutes C = 0. Mom + 39. 99 Plan S: Let c = cost In collars C = 0. Mm + 59. 99 Let = cost in dollars C = Ron + 69. 99 4. 5. Susan is a Sprint customer and wants to switch to AT&T. She must decide which phone plan best suites her. Examine the graphs and equations. Advise Susan on her choices by explaining, in writing, which plan is best for a certain number of minutes. Susan plans to use 100 minutes in a month: Plan A: C = 0. Mom + 39. 99 with 450 minutes included . C = \$39. 99 Plan B: C = 0. Mom + 59. 99 with 900 minutes included . C = \$59. 99 Plan C: C = Mm + 69. 99 for unlimited minutes. C = \$69. 99 If Susan plans to use 100 minutes, she should use Plan A.

Susan plans to use 500 minutes in a month: 00 minutes – 450 minutes = 50 minutes of overage. C = 0. 45(50) + 39. 99 c = \$62. 49 If Susan plans to use 500 minutes, she should use Plan B. Susan plans to use 1500 minutes in a month: 1500 minutes – 450 minutes = 1050 minutes of overage c = \$512. 49 1500 minutes – 900 minutes = 600 minutes of overage c = 0. 40(600) + 59. 99 c = \$299. 99 If Susan plans to use 1500 minutes, she should use Plan C. Homework/Extension Compare the three plans above too prepaid plan. Using the \$0. 10 per minute plan, create the table of values and graph as you did for the previous three cell phone plans. 5 45 75 105 120 Nat trend ay you notice? 5. Calculate the rate of change in price for this plan.