The cost of using a telephone in a hotel meeting room is $0.20 per minute. Which of the following equations represents the total cost c, in dollars, for h hours of phone use?
The hotel charges 0.20 per minute to use the meeting room phone. This per-minute rate can be converted to the hourly rate using the conversion 1 hour = 60 minutes, as shown below.
Thus, the hotel charges per hour to use the meeting-room phone. Therefore, the cost c, in dollars, for h hours of use is , which is equivalent to Choice B is incorrect because in this expression the per-minute rate is multiplied by h, the number of hours of phone use. Furthermore, the equation indicates that there is a flat fee of in addition to the per-minute or per hour rate. This is not the case. Choice C is incorrect because the expression indicates that the hotel charges per hour for use of the meeting room phone, not per hour. Choice D is incorrect because the expression indicates that the hourly rate is times the per-minute rate, not 60 times the per-minute rate.