The economy grew 2.5% in the third quarter, a quick-enough pace to blunt fears that the U.S. is about to plunge into recession again but not fast enough to signal that the halting recovery is about to get on a roll. The rise in gross domestic product—the sum of all goods and services produced—suggests the U.S. found its footing after events earlier this year, including a surge in gasoline prices and waves of stock-market turmoil, led wary consumers and businesses to pull back on spending.