Stock prices declined slightly in quiet trading today, marking time after last week's rise to a record high. The Dow Jones average of 30 industrials dropped 7.18 to 2,812.73 in the first half hour of trading. Losers outnumbered gainers by about 7 to 5 in nationwide trading of New York Stock Exchange-listed issues, with 405 up, 566 down and 501 unchanged. Volume on the Big Board came to 17.80 million shares as of 10 a.m. on Wall Street. Analysts said there was little in the news to encourage buyers to chase after the market's recently rally. Interest rates were mixed to slightly higher in the credit markets this morning. Yields on long-term government bonds hovered in the 8.70 percent-8.74 percent range. The upsurge in stock prices since the end of April has been attributed largely to a downturn in interest rates, and accompanying assurances that the Federal Reserve seemed less and less likely to tighten credit. In the past few days, however, rates have levelled off, and investors apparently have settled back to await signs of their next likely move. K mart dropped \ to 34. The company reported earnings for the fiscal quarter ended May 2 of 50 cents a share, against 47 cents in the comparable period a year earlier. The NYSE's composite index of all its listed common stocks slipped .11 to 193.44. At the American Stock Exchange, the market value index was up .38 at 356.70. On Friday the Dow Jones industrial average dropped 11.80 to 2,819.91, reducing its gain for the week to 18.33 points. Advancing issues slightly outnumbered declines on the NYSE, with 745 up, 716 down and 526 unchanged. Big Board volume totaled 162.52 million shares, against 164.77 million in the previous session.