Answer
(a) increase
(b) $464Hz$
Work Step by Step
(a) We know that the frequency is inversely proportional to the length of the air column, so the fundamental frequency increases as the length of the air column is decreased.
(b) The fundamental frequency can be determined as
$f_1=\frac{v}{4L}$
We plug in the known values to obtain:
$f_1=\frac{343}{4(0.260-0.075)}=464Hz$
