What single sum of money occurring at t = 5 will be equivalent to a cash flow series consisting of \($7\),000 at t = 1, \($6\),000 at t = 2, \($5\),000 at t = 3, \($4\),000 at t = 4, \($3\),000 at t = 5, \($2\),000 at t = 6, and \($1\),000 at t = 7, based on an interest rate of

a. 6 percent.

b. 10 percent.