Demographic trends across the country are favorable to colleges, but they present challenges to institutions in both low- and high-growth states, according to a report released on Wednesday by Moody’s Investors Service. Those likely to fare well in the coming years are public flagship universities, community colleges in growing areas, top-tier private institutions, and comprehensive urban universities. Institutions likely to face challenges, according to the report, are regional public universities in slow-growth states, community colleges is areas with declining populations, and small private colleges without large endowments, especially in the Northeast and Midwest. Copies of the report can be obtained by sending an e-mail message to John Cline, vice president for rating communications at Moody’s.