WASHINGTON — Mortgage rates dropped this week as investors became less worried that the Federal Reserve is about to tighten credit policy to stall inflation.

Mortgage company Freddie Mac reported yesterday that 30-year fixed-rate mortgages averaged 6.26 percent this week, down from 6.37 percent last week.

Other rates dropped as well, according to Freddie Mac's nationwide survey. Rates on 15-year fixed-rate mortgages dipped to 5.78 percent, from 5.91 percent last week.

Rates on five-year adjustable-rate mortgages fell to 5.80 percent, down slightly from 5.82 percent, and rates on one-year ARMs dropped to 5.10 percent, from 5.17 percent last week.