Question

A parking garage charges $5.50 to park for 4 hours and $7.75 to park for 7 hours. If the cost is a linear function of the number of hours parked, what is the cost to park for 3 hours?
$2.25
$2.50
$3.25
$4.75

Answer 1

Cost is linear: slope = (7.75 − 5.50)/(7 − 4) = 2.25/3 = 0.75 per hour.
So cost = 0.75h + b. Using h=4: 5.50 = 0.75·4 + b → b = 2.50.
For 3 hours: cost = 0.75·3 + 2.50 = 2.25 + 2.50 = 4.75.

Answer: $4.75