In Exercise 2.4 it tells you that the discount rate is 10%.  Through my studying for the FM exam I know that what they call the discount rate (usually denoted 'd') something different...  d = i / (1+i)

Just for clarification, everytime you talk about the discount rate for homework, tests, etc.  You will be meaning the interest rate used to discount the payments correct?  Just making sure this terminology will not switch back and forth.