Chemistry problem/percent by mass?

Question

Copper metal can be recovered from an ore containing CuCO3 by the decomposition reaction:

2 CuCO3 --------> 2 Cu + 2 CO2 + O2

What mass of copper ore, in tons, is needed to produce 500.0 lb of Cu if the ore is 13.22% by mass CuCO3? Assume complete decomposition of the CuCO3.

I solved the problem to 0.4861 tons of CuCO3 needed to produce 500.0 lb Cu. I'm not sure that's correct, because when I tried to use the 13.22% by mass of the ore to calculate how much ore is needed, I got an answer different from on the answer key. Help?

Here's the conversions I'm using:

1 kilogram = 10^3 grams
1 kilogram = 2.205 lbs.
2000 pounds= 1 ton

Cu = 63.55 g/mol
CuCO3 = 123.56 g/mol

The answer on the answer key is .03677 tons.

Answer 1

Atomic weights: Cu=63.5 C=12 O=16 CuCO3=123.5 Let the ore be called R. Let the molecular weight expressed in lb be called a lbmol.

500.0lbCu x 1lbmolCu/63.5lbCu x 2lbmolCuCO3/2lbmolCu x 123.5lbCuCO3/1lbmolCuCO3 x 100lbR/13.22lbCuCO3 x 1TR/2000lbR = 3.678 T ore

Answer 2

the answer should BE 3.68 TONS! I think you keep forgetting to use the 13.22% by mass, this means that you have x amount of tons and only 13.22% of that will be used so .1322X = tons of cuc03... there for revealing 3.68 tons!