Standing Waves on a String: a Heavy Stone of Mass

Multiple Choice

Standing waves on a string: A heavy stone of mass m is hung from the ceiling by a thin 8.25-g wire that is 65.0 cm long. When you gently pluck the upper end of the wire, a pulse travels down the wire and returns 7.84 ms later, having reflected off the lower end. The speed of sound in the room is 344 m/s, and the stone is heavy enough to prevent the lower end of the wire from moving. If the wire is vibrating in its second overtone, what is the frequency of the sound it will produce?

A) 128 Hz
B) 191 Hz
C) 255 Hz
D) 383 Hz
E) 765 Hz