T-Bill Rates Rise: The Treasury sold $7.2 billion of new three-month bills at an average discount rate of 9.1%, up from 9% last week. Another $7.2 billion of six-month bills was sold at an average discount rate of 9.12%, up from 9.04% last week. The rates were the highest since three-month bills sold for 9.38% and six-month bills averaged 9.59% on Oct. 29, 1984. The new rates understate the actual return to investors--9.44% for three-month bills, with a $10,000 bill selling for $9,770.00 and 9.69% for six-month bills selling for $9,538.90. The discount rate reflects the price discount received when government securities are purchased at less than face value.