The dollar jumped today, showing one of the largest one-day gains of the year against the German mark . . . Dow Jones industrial average up51.16 points, closing at 3881.05 . . . N.Y.S.E.'s composite index up 2.64, to 260.82 . . . NASDAQ stock up 8.14, to 762.94 . . . American Stock Exchange up 2.44, to 449.56 . . . Gold stayed at $383.30 on the Commodity Exchange in New York . . . The 30-year Treasury bond closed with a yield of 7.47 percent, down from 7.53 late Thursday.