Answer:
3.12 m
Step-by-step explanation:
The fundamental frequency of an open-closed tube is given by

where
f1 is the fundamental frequency
v is the speed of sound in air (343 m/s)
L is the length of the tube
If we use the model mentioned, we can consider L to be the effective length of the instrument. This means we can re-arrange the formula and use the fundamental frequency, f1 = 27.5 Hz, to find L:
