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
![f = (v)/(\lambda)](https://img.qammunity.org/2020/formulas/physics/college/ezivdofqy9e2s0w93ntstmep2f3h7odaa6.png)
Where,
v = Velocity
Wavelength
Our value are given by,
v = 345m/s
![\lambda = 63cm](https://img.qammunity.org/2020/formulas/physics/college/bjikb1opl4nze35ngtsyst8sszh7w00isa.png)
Replacing
![f = (345)/(0.63)](https://img.qammunity.org/2020/formulas/physics/college/ugfsnp4pq3prsoygsfu0dhrvhpnnwrsdvk.png)
![f = 547.61Hz](https://img.qammunity.org/2020/formulas/physics/college/dfpfnlyse74hdgdce0uqkc6zqx3z8e7hcb.png)
Therefore the frequency of the tuning fork is 547.61Hz