Math Forum - Problem of the Week


TI-PoW: A Phone-y Deal?

With cell phones being so common these days, the phone companies are all competing to earn business by offering various calling plans.

One of them, Horizon, offers 700 minutes of calls per month for $45.99, and additional minutes are charged at 6 cents per minute.

Another company, Stingular, offers 700 minutes for $29.99 per month, and additional minutes are 35 cents each.

Use your TI-Nspire™ to help you answer the questions below:

  1. For each plan, write an expression that represents the total cost per month in terms of the number of additional minutes used.

  2. For how many total minutes of calls per month is Horizon's plan a better deal?

Extra: A third company, Dash, offers a plan that costs $49 for 500 minutes, and extra minutes are 2 cents each. For how many total minutes of calls per month is the Dash plan the best deal of the three?


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