Sources of musical sound problem

[mikejones2000]

Question: Organ pipe A, with both ends open, has a fundamental frequency of 450 Hz. The third harmonic of organ pipe B, with one end open, has the same frequency as the second harmonic of pipe A. Use 343 m/s for the speed of sound in air.
a)How long is pipe A?

b)How long is pipe B?

I found the length of pip a by f=v/2L, or 450=343/2L, L=343/900, which is correct.

I thought I could find the length of pipe B by setting an equality like this: (5v/4L)=(2v/2(.381)). I am pretty sure I did the algebra correctly but got an incorrect answer. Any help would be greatly appreciated...

 

[J Hann]

Fundamental frequency of pipe A = 450/s
First harmonic " = 900/s
Second harmonic " = 1350/s

Fundamental length of pipe B = 1/4 wavelength
|
|
Length of pipe B for 3d harmonic = 7/4 wavelength

Solve just as you solved for the length of pipe A