The cost to park a car in a certain parking garage is $9.00 for up to 2 hours of parking and $1.75 for each hour in excess of 2 hours. What is the average (arithmetic mean) cost per hour to park a car in the parking garage for 9 hours? Choose one
A) $ 1.09  B) $ 1.67  C) $ 2.25  D) $ 2.36  E) $ 2.50

Rationale: "total cost of parking for 9 hours = 9 $ for the first 2 hours and then 1.75 for ( 9 - 2 ) hours = 9 + 7 * 1.75 = 21.25 thus the average parking price = 21.25 / 9 = 2.36 $ d is the correct answer ."
Answer: D