Answer:
349 Hz
Step-by-step explanation:
We are told that the guitar string produces 3 beats/s when sounded with a 352 Hz tuning fork and 8 beat/s when sounded with a 357 Hz tuning fork.
This means that for the 352 Hz tuning fork, the vibrational frequency is;
f = 352 ± 3
f = (352 + 3) or (352 - 3)
f = 355 Hz or 349Hz
For the 357 Hz tuning fork, the vibrational frequency is;
f = 357 ± 8
f = (357 + 8) or (357 - 8)
f = 365 Hz or 349 Hz
In both cases, 349 Hz is common;
Thus, the vibrational frequency of the string = 349 Hz