WASHINGTON (MarketWatch) - The number of job openings in the United States slipped in September for the fourth month in a row to 7.02 million from 7.3 million, the government said Tuesday. Openings have declined as companies cut back on hiring with the U.S. economy growing more slowly. The percentage of people in the private sector who chose to leave their old jobs, known as the quit rate, edged down to 2.6% from 2.7%. It fell to 2.3% from 2.4% for all workers including government employees.