SOLUTION: the monthly cost in dollars of a long-distance phone plan is a linear function of the total calling time in minutes. The monthly cost for 43 minutes is $13.42 and the monthly cost

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: the monthly cost in dollars of a long-distance phone plan is a linear function of the total calling time in minutes. The monthly cost for 43 minutes is $13.42 and the monthly cost       Log On


   

Question 1198073: the monthly cost in dollars of a long-distance phone plan is a linear function of the total calling time in minutes. The monthly cost for 43 minutes is $13.42 and the monthly cost for 91 minutes is $19.66. What is the monthly cost for 55 minutes?
Answer by ikleyn(52790) About Me  (Show Source):
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the monthly cost in dollars of a long-distance phone plan is a linear function
of the total calling time in minutes.
The monthly cost for 43 minutes is $13.42 and the monthly cost for 91 minutes is $19.66.
What is the monthly cost for 55 minutes?
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The price per minute is  m = %2819.66-13.42%29%2F%2891-43%29 = 0.13 dollars per minute.


The montly cost for 55 minutes is  13.42 + m*(55-43) = 13.42 + 0.13*(55-43) = 14.98  dollars.    ANSWER

Solved.