Power systems are rated for nominal voltages such as: 120, 208, 240, 480, and 600V. These voltages are specified by ANSI and have been the "correct" voltages to use since the early 1950's.
110.4 says in part "...nominal voltage of a circuit..."
220.2 says "Unless other voltages are specified, for purposes of computing... nominal voltages ... shall be used."
Motors are rated for utilization voltages (they allow for voltage drop from nominal) of: 115, 200, 230, 460, and 575V. These are the nameplate voltages referred to in Articles 430 and 440.
In my opinion, the question was intended to test the knowledge of the formula (va = volts x amps). Art 220.2 gives the writer the authority to specify the voltage (yes it appears to be a trick question).
