The Treasury Department sold $6.6 billion in new three-month bills at an average discount rate of 5.66%, down from 5.72% last week. Another $6.6 billion was sold in new six-month bills at an average discount rate of 5.70%, up from 5.69% last week. The rates for three-month bills were the lowest since Feb. 2 when they averaged 5.58%. The rates on six-month bills were the highest since Aug. 4 when they averaged 5.73%. The new discount rates understate the actual return to investors--5.82% for three-month bills with a $10,000 bill selling for $9,856.90 and 5.95% for six-month bills selling for $9,711.80. The discount rate reflects the price discount received when government securities are purchased at less than face value.