Why are currency exchange ratesnecessary among global trading nations? What are the most required characteristics for exchange rates to be viable for use in global business?

What does "velocity" mean as it relates to the money supply? Suppose there is an increase in the money supply by government policy by the velocity is unpredictable, what are the implications of this to the economy?

Suppose PeopleBank has deposit liabilities of $120 million, and a reserve ratio of 20 percent. Its annual costs (wages, rent, utilities, etc.) are $3 million. What is PeopleBank's profit if it charges 11 percent annual interest on its loans outstanding, and pays 3 percent interest on its deposits? Please show your calculations. Thanks