HotFoot Shoes would like to maintain their cash account at a minimum level of $25,000, but expect

Question:

HotFoot Shoes would like to maintain their cash account at a minimum level of $25,000, but expect the standard deviation in net daily cash flows to be $4,000, the effective annual rate on marketable securities to be 6.5 percent per year, and the trading cost per sale or purchase of marketable securities to be $200 per transaction. What will be their optimal cash return point?