problem in AS physics

[rasesh popat]

can anyone help me with the question of physics paper 22, of oct-nov 2009, question 4-(c)-(ii)-2,[page-13]. I tried solving but came with incorrect answer, even in the mark scheme of the paper, the method is wrong. Please help me.

 

[ChrisChin]

Actually, the marking scheme is correct.

At the lowest frequency, the wave produced in a tube with one closed end is a standing wave with only an antinode at the open end and a node at the closed end. This represents only a quarter of a full wave, so the length of the tube is 1/4 of the wavelength.

.: λ = 4 x L = 4 x 0.45m = 1.8m

v = fλ, => 330 = f x 1.8
.: f = 330/1.8 = 180Hz