Let's assume the density of the specific crusher run is 2500 lbs/yd³. Using the formula provided, we can calculate the amount of crusher run needed: CR = (50 x 10 x 0.5) x 1.25 / (2500 / 2000) ≈ (250) x 1.25 / 1.25 = 250 tons. So, for this particular area, approximately 250 tons of crusher run gravel would be require.