The Treasury Department sold $7.2 billion in new three-month bills at an average discount rate of 7.17%, down from 7.22% last week. Another $7.2 billion was sold in new six-month bills at an average discount rate of 7.32%, down from 7.39% last week. The rates were the lowest since Sept. 3, when three-month bills sold for 7.12% and six-month bills averaged 7.3%. The new discount rates understate the actual return to investors--7.4% for three-month bills and 7.71% for six-month bills. The discount rate reflects the price discount received when government securities are purchased for less than face value.