text: OK. We know 558g of iron were obtained. 1 mol of iron weighs 55.8g, so 10moles of iron were obtained.\n\n5Fe203 + 15CO -> 10 Fe + 15 CO2\n\nSo we must have had 5moles of Fe2O3 in the original sample. \n1 mole of Fe2O3 weighs 160g (given)\n5 moles weighs 800g\n\nAnd, in the original sample of ore, 800 out of 1600g was Fe2O3 - or 50%