The annual revenues (in $1000 units) associated with several large apartment complexes are $0, $350, $290, $460, $150, and $320 for years 0, 1, 2, 3, 4, and 5, respectively. Determine

(1) Whether each cash flow series is conventional or nonconventional,

(2) The maximum number of real-number roots, and

(3) If there is one, positive real-number i* value. The cash flows for years 0, 1, 2, 3, 4, and 5, respectively, are:

(a) $−1500, $−90, $−40, $−85, $−60, and $−90

(b) $−1500, $−450, $−300, $−400, $−125, and $−400

(c) $1500, $−450, $−300, $−500, $−200, $−400

(d) $−1500, $−450, $−300, $−400, $−125, and $−310