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Cell phone minutes mathematics problem?
A cellular phone company offers a contract for which the cost C, in dollars, of t minutes of telephoning is given by C=0.25(t-300)+60.95, where it is assumed that t≥300 minutes.
What time will keep costs between $104.20 and $125.20?
For the cost to be between $104.20 and $125.20, the telephoning time must be between __ minutes and __ minutes.
2 Answers
- 1 decade agoFavorite Answer
Must be between 473 minutes and 557 minutes
C = .25t - 75 + 60.95 (distribute .25)
C = .25t - 14.05 (combine like terms)
104.20 = .25t - 14.05 (solve for minimum)
118.25 = .25t (add 14.05 to both sides)
473 = t (divide both sides by .25)
104.20 = .25t - 14.05 (solve for maximum)
139.25 = .25t (add 14.05 to both sides)
557 = t (divide both sides by .25)
Source(s): Math teacher
