A person places the speakers 4.0 m apart and connects a signal generator to both speakers that produces a single and consistent tone. (constant wavelength and frequency) He then walks to a point that is 2.0 m from one speaker and 2.3 m from the other. At that point he notices a quiet “spot”. If the speed of the sound in the room is known to be 350 m/s, calculate the possible frequencies being played by the speakers.

Question

A person places the speakers 4.0 m apart and connects a signal generator to both speakers that produces a single and consistent tone. (constant wavelength and frequency)  He then walks to a point that is 2.0 m from one speaker and 2.3 m from the other. At that point he notices a  quiet “spot”.  If the  speed of the sound in the room is known to be 350 m/s, calculate the possible frequencies being played by the speakers.

My Answer:
PD=2.3m-2m
PD=.3m

PD=(n-.5) λ,      but λ=v/f
PD=(n-.5)(v/f)
.3=(n-.5)(350/f)
f=(n-.5)(350/.3)
f=(n-.5)(3500/3)
f=(3500n/3)-(3500/6)

f=(3500n/3)-(3500/6), where n is any real integer.

Is this right? Thanks for your help.