The Treasury Department sold $7.2 billion in new three-month bills at an average discount rate of 5.08%, down from 5.20% last week. Another $7.2 billion was sold in new six-month bills at an average discount rate of 5.13%, down from 5.37% last week. The rates were the lowest since three-month bills sold for 5.04% on July 1, 1977, and six-month bills averaged 5.05% on May 2, 1977. The new discount rates understate the actual return to investors--5.22% for three-month bills and 5.34% for six-month bills. The discount rate reflects the price discount received when government securities are purchased at less than face value.