Answer
a. 360 Hz
b. 540 Hz
Work Step by Step
a. See figure 12-12. For a pipe that is closed at one end, the fundamental frequency is $f_1=\frac{v}{4 \mathcal{l}}$.
$f_1=\frac{343 m/s}{4 (0.24m)}=360Hz$
b. If the bottle were one-third full of soda, the effective length of the air column would now be 16 cm.
$f_1=\frac{343 m/s}{4 (0.16m)}=540Hz$
