Some of the lowest pitches attainable on a musical instrument are achieved on the world’s largest pipe organs. What is the length of an organ pipe that is open on both ends and has a fundamental frequency of 8.75 Hz when the speed of sound in air is 341 m/s?
(a) 9.83 m (c) 21.2 m (e) 32.4 m
(b) 19.5 m (d) 29.3 m

Question

Some of the lowest pitches attainable on a musical instrument are achieved on the world’s largest pipe organs.  What is the length of an organ pipe that is open on both ends and has a fundamental frequency of 8.75 Hz when the speed of sound in air is 341 m/s?
	(a)	9.83 m	(c)	21.2 m	(e)	32.4 m
	(b)	19.5 m	(d)	29.3 m

anonymous · Answer

T = 1/f
T - periof, f - frequency
T = 0,114 sec

L = V * T

L = 38,97 m

since it's open on both sides, then divide by 2 and the answer is 19,485 m

So the answer is B.