The density of noble metals is traditionally expressed in grams per cubic centimeters. So, 10.725 kilograms = 10725 grams, and 0.0005 m^3 = 0.5 dm^3 = 500 cubic centimeters, so the density == 21.45 g/cm^3. ANSWER CHECK. Internet sources give the same value. https://hypertextbook.com/facts/2004/OliviaTai.shtml