You have two alternatives for a $180$ day deposit. You can invest for the full $180$ days at a rate of $6\mathrm{.}38\%$ or buy a $90$ day Eurodollar CD paying $6\mathrm{.}23\%$ plus a $90$ day futures contract on a $90$ day Eurodollar CD with an implied yield of $6\mathrm{.}72\%.$