Question

When designing an arena, architects designed the ramps leading up to the entrances so that circus elephants would be able to walk up the ramps. The maximum grade (or slope) that an elephant will walk on is 13%. Suppose that such a ramp was constructed with a horizontal run of 80 ft. What would be the maximum vertical rise the architects could use?

Answer 1

The maximum vertical rise would be 10.4 ft.

A 13% grade is the slope, or rise/run.

13% = 13/100

Setting up a proportion with the 80 ft horizontal run and an unknown rise, we have:
13/100 = x/80

Cross multiplying we have
100*x = 13*80
100x = 1040

Divide both sides by 100:
100x/100 = 1040/100
x = 10.4