WASHINGTON (Reuters) -U.S. economic growth slowed in the fourth quarter as a strike at Boeing contributed to depressing business investment, but robust consumer spending probably keeps the Federal Reserve on a slow interest rate cut path this year. The moderation in growth last quarter reported by the Commerce Department on Thursday was also because inventories at businesses were run down, underscoring the strong domestic demand. There was a surprise drop in imports, despite imports helping to boost the goods trade deficit to a record high in December, which had prompted economists to sharply downgrade their fourth-quarter growth estimates.