Answer :
To develop this problem it is necessary to apply the concept of Frequency based on speed and wavelength.
According to the definition the frequency can be expressed as
[tex]f = \frac{v}{\lambda}[/tex]
Where,
v = Velocity
[tex]\lambda =[/tex] Wavelength
Our value are given by,
v = 345m/s
[tex]\lambda = 63cm[/tex]
Replacing
[tex]f = \frac{345}{0.63}[/tex]
[tex]f = 547.61Hz[/tex]
Therefore the frequency of the tuning fork is 547.61Hz