The mass use of credit cards began in 1958 with the BankAmericard. Its name changed in 1976 to

An economic model is useful if it

a. includes every detail of reality b. involves no unproven assumptions c. is expressed in equations d. makes accurate predictions e. is simple enough to be understood by a child

The natural rate of unemployment:

A. is typically zero. B. is the normal level of unemployment in an economy in the long run. C. is constant over time. D. None of these is true.