A microphone is connected to a cathode-ray oscilloscope (CRO). When a tuning fork is struck and then held next to the microphone, the following waveform is shown on the display of the CRO. [Figure showing a CRO screen displaying a sinusoidal waveform with 4 divisions per complete cycle] The time-base setting on the CRO is 2.00 ms per division. What is the best estimate of the frequency of the sound produced by the tuning fork?

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