Twelve
For an open ended pipe, the fundamental frequency is dependent on the length of the pipe and the speed of sound. Slightly less dramatic limiting factors are the temperature and pressure.
In an open pipe column, the fundamental frequency is f1 = V_sound / (2*L) which means that the longer the pipe, the lower the frequency.
Each frequency thereafter is just a multiple of the fundamental frequency.
f2 = 2* f1
f3 = 3 * f1
fn = n*f1
But that is not really what you are being asked. You are asked about the wavelength
Start with the fundamental formula
v = f wavelenght
f = n * v/2L
v = (n*v/2L) * wavelength The "v"s cancel out
2L / n = wavelength.
Thirteen
Fourteen
If the pipe increases in length, the frequency will go down and the wavelength will go up
