$.$ How can the provision of several types of financial services by one firm be both beneficial and problematic? $2.$ In prison, cigarettes are sometimes used among inmates as a form of payment. How is it possible for cigarettes to solve the "double coincidence of wants" problem, even if a prisoner does not smoke? $.$ Retired persons often have much of their wealth placed in savings accounts and other interest$-$bearing investments, and complain whenever interest rates are low. Do they have a valid complaint? $4.$ What effect will a sudden increase in the volatility of gold prices have on interest rates? s$.$ How might a sudden increase in people's expectations of future real estate prices affect interest rates?