   SEARCH HOME Math Central Quandaries & Queries  Question from Dawn, a parent: What is a better deal for topsoil, $150.00 for 10 cubic yards,$170.00 for 22 tons, or $200.00 for 11.5 yards? Hi Dawn, When contractors say yards when talking about topsoil, concrete or similar materials they mean cubic yards. Thus the first choice is$150.00/10 = $15.00 dollars per cubic yard and the third choice is$200/11.5 = $17.39 dollars per cubic yard. Thus the first choice is less expensive than the third. For the second choice I suggest you call the contractor and ask how many yards are in 22 tons. You can do the calculation yourself if you know the density of the topsoil being delivered. I found some information on the reade.com web site. Look under E for earth. The last column is in pounds per cubic foot but Google can help here. For example for Earth, moist, excavated the density is given as 90 pounds per cubic foot. Go to Google and type 90 pounds per cubic foot in tons per cubic yard into the search window. Google responds with (90 pounds) per (cubic foot) = 1.21500 short tons per (cubic yard). Hence if this is the correct density 22 tons = 22/1.215 = 18.1 cubic yards which at$170.00 is

170/18.1 = 9.39 dollars per cubic yard.

I hope this helps,
Penny     Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.