Chromel is an alloy composed of nickel, iron, and chromium. A 0.6473 g sample was dissolved and diluted to 250.00 mL. When a 50 mL aliquot of 0.05182 M EDTA was mixed with an equal volume of the diluted sample, all three ions were chelated, and a 5.11 mL back-titration with 0.06241 M copper (II) was required. The chromium in a second 50 mL aliquot was masked through the addition of hexamethylenetetramine; titration of the Fe and Ni required 36.28 mL of 0.05182 M EDTA. Iron and chromium were masked with pyrophosphate in a third 50 mL aliquot, and the nickel was titrated with 25.91 mL of the EDTA solution. Calculate the percentages of nickel, chromium and iron in the alloy.