Copper ended up over 2 percent on Friday, posting its biggest weekly advance since early December, as the dollar weakened and investor demand for the metal increased with inflation fears mounting. COMEX May copper surged 8.50 cents, or 1.9 percent, to settle at $4.5015 per lb. For the week, prices were up about 5.7 percent - their largest weekly gain since the first week of December 2010.