SOLUTION: Mary is certain that every time she parks in the parking lot it costs her $2.45. If the garage charges 45cents plus 25cents for each 1/2 hour, how long is she parked? The pr

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: Mary is certain that every time she parks in the parking lot it costs her $2.45. If the garage charges 45cents plus 25cents for each 1/2 hour, how long is she parked? The pr      Log On


   

Question 352449: Mary is certain that every time she parks in the parking lot it costs her $2.45. If the garage charges 45cents plus 25cents for each 1/2 hour, how long is she parked?
The problem does not state if the first hour is 45 cents and then every 1/2 is 25; so I am assuming it is 70cents per half hour. Is that correct? If so, I would say she was parked 3 1/2 hours. Is that correct?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let t = # of hours car is parked

Since "the garage charges 45cents plus 25cents for each 1/2 hour", this means that the garage initially charges 0.45 dollars (regardless of time parked) plus 0.5t dollars (since she's charged 50 cents an hour)


So the cost equation is c=0.5t%2B0.45


Since we're given that "it costs her $2.45", we know that c=2.45.



c=0.5t%2B0.45 Start with the given equation.


2.45=0.5t%2B0.45 Plug in c=2.45


245=50t%2B45 Multiply EVERY term by 100 to make each number a whole number.


245-45=50t Subtract 45 from both sides.


200=50t Combine like terms.


200%2F50=t Divide both sides by 50.


4=t Reduce


So the solution is t=4


This means that she parked her car for 4 hours.


If you need more help, email me at jim_thompson5910@hotmail.com

Also, feel free to check out my tutoring website

Jim