Four beats per second are heard when an unknown tuning fork and a 240 hz tuning fork are struck simultaneously. this same unknown tuning fork and a 250 hz tuning fork are struck. six beats are heard. its exact frequency: is 256 hz is 236 hz is 244 hz cannot be determined

When the tuning forks are struck simultaneously, the beat frequency is equal to the absolute value of the difference between the frequencies of the two tuning forks:

where  is the beat frequency, and  are the frequencies of the two forks.

In the first part of the problem,  and , with  being the frequency of the unknown fork. In the second part of the problem,  and . So we have the following system of two equations:


and the solution of this system is 

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