A musician using an open flute of length 50 cm produces second harmonic sound waves. A person runs towards the musician from another end of a hall at a speed of 10 km/h. If the wave speed is 330 m/s, the frequency heard by the running person shall be close to:
(1) 666 Hz
(2) 753 Hz
(3) 500 Hz
(4) 333 Hz