The U.S. economy grew 3% in the fourth quarter, faster than originally reported, mainly because of increased commercial construction and consumer spending and lower imports, the U.S. Commerce Department reported today. Economists polled by Reuters had expected fourth-quarter GDP would be unrevised at a 2.8% pace. The economy grew at a 1.8% pace in the third quarter. While the build-up in business inventories still accounted for much of rise in output in the last quarter, the revisions to GDP unveiled an improved tone for the first-quarter growth outlook. Businesses were not as aggressive in their restocking efforts, which should help to allay fears of a sharper slowdown in output this quarter.