The economy added 169,000 jobs in August, a modest gain but hardly enough to signal robust job growth. The U.S. unemployment rate fell to 7.3 percent from 7.4 percent. But the decline was mostly because more people stopped looking for work and were no longer counted as unemployed.A weaker outlook for the rest of the year was a key reason the Federal Reserve decided last week to hold off on slowing its $85-billion-a-month in bond purchases. The bond purchases have kept longer-term interest rates low, making mortgages and other consumer loans more affordable. Many economists believe the Fed won't reduce the bond purchases until December at the earliest. The economy has been held back this year by tax hikes, federal spending cuts and weaker global growth. It expanded at an annual rate of 2.5 percent in the April-June quarter. But many economists say growth is slowing in the July-September quarter to an annual rate of 2 percent or less.