Existing single-family homes in California were sold at a seasonally adjusted annual rate of 439,816 units in July, up 7.5% from June's 409,288-unit yearly pace and 19.9% above the 366,800-unit rate in July of last year, the California Assn. of Realtors said. The sales rate had tumbled 20.4% in June. The association cited lower interest rates and the clearing of backlogs by lenders, appraisers and others involved in the real estate business. The median price of a home in California last month was $137,117, virtually unchanged from the June median of $137,392.