solve to find time in hours and days. show the units and dimensional analysis

Question

The permeability of sand is 0.001 cm/s. If a chemical herbicide is spilled on a sandy soil, how long (in hours) will it take for the contaminant to reach a water supply well 150 feet away?

Assume that sand has constant permeability in area herbicide moves per permeability of sand.

Answer 1

(0.001 cm/s)(1 in/2.54cm)(1 ft/12 in)(3600 s/1 hr) =  0.118 ft / hr

then

0.118ft / hr = 150 ft / x hrs

x = 150 / 0.118 = 1271.2 hrs or 52.9 days