I need help in physics What is the frequency of the sound? Assume the speed of sound...

...is 340 m/s.? Two loudspeakers located along the x-axis as shown in the figure produce sounds of equal frequency. Speaker 1 is at the origin, while the location of speaker 2 be varied by a remote control wielded by the listener. He notices maxima in the sound intensity when speaker 2 is located at x1 = 0.700 m and 1.15 m, but at no points in between.

http://session.masteringphysics.com/problemAsset/1014422/8/jfk.Figure.P16.59.jpg

What is the frequency of the sound? Assume the speed of sound is 340 m/s.

Well, because you were given that 2 maxima in the sound intensity occur at x = .7 m and 1.15 meters, you can subtract these two numbers and get the wavelength. When you do you get .45 meters. Then just use the formula v = f*lambda, where v = speed of sound, f = frequency and lambda = .45 meters. Consequentially, you get (340) = f*(.45), so f = 755.56...