Organ pipe A$,$ with both ends open, has a fundamental frequency of $400$ 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$?$

m

$($b$)$ How long is pipe B$?$

m