The American with Disabilities Act (ADA) requires that the slope of a wheelchair ramp be no greater than 1:12. Which of the following is the minimum length of a ramp needed to provide access to a door that is 5.2 feet above the sidewalk?
A. 52 feet
B. 148 feet
C. 32.2 feet
D. 62.4 feet
In this problem slope represents the change in height above sidewalk to change in length of the ramp.
From the definition of slope
Letting x to be the minimum length of the ramp, then
Substituting with the known value of slope
Cross-multiply to find the value of x
Thus, the minimum length of the ramp needed is 62.4 feet to access to a door that is 5.2 feet above the sidewalk.
Therefore, the Correct Answer is D.