The spread between the average and lowest mortgage rates being offered in the primary market is continuing to widen as lenders try to get customers to take advantage of the record-low rates either for purchasing a home or refinancing. While the average mortgage rates remained in the 4.22 percent to 4.28 percent range for a 30-year fixed-rate mortgage across the country, the most aggressive lenders are offering rates as low as 3.88 percent, according to mortgage brokers. The Lending Tree Weekly Mortgage Rate Pulse, which tracks the lowest and average mortgage rates offered by lenders on the company’s network, recently reported...