SOLUTION: A cellular phone compnay offers a contract for which the cost C, in dollars, of t minutes of telephoning is given by C=0.25(t-300)+46.95, where it is assumed that t>300 minutes. Wh

Algebra ->  Systems-of-equations -> SOLUTION: A cellular phone compnay offers a contract for which the cost C, in dollars, of t minutes of telephoning is given by C=0.25(t-300)+46.95, where it is assumed that t>300 minutes. Wh      Log On


   

Question 138767: A cellular phone compnay offers a contract for which the cost C, in dollars, of t minutes of telephoning is given by C=0.25(t-300)+46.95, where it is assumed that t>300 minutes. What times will keep cost between $ 95.20 and $124.20?
For the cost to be between $ 95.20 adn $124.20,the telephoning times must be between ___ minutes and ___ minutes.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
C=0.25(t-300)+46.95, where it is assumed that t>300 minutes. What times will keep cost between $ 95.20 and $124.20?
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95.20 < 0.25(t-300) + 46.95 < 124.20
Subtract 46.95 along the line to get:
48.25 < 0.25(t-300) < 77.25
Divide thru by 0.25 to get:
193 < t-300 < 309
Add 300 along the line to get:
493 < t < 609
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If you assume t>300 the answer becomes:
300 < t < 609
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Cheers,
Stan H.