48. Assume that short-term investment securities are yielding 5 percent, and it costs a fimm $20 each time it buys or sells investment securities. The variance of the firm's daily net cash flows has been found to be $20,000. Management wants to keep at least $1,000 in the cash account for emergencies. Given these conditions, what is the upper limit? D$4345 S4975 54,097 5434