Beats: Two harmonic sound waves reach an observer simultaneously. The observer hears the sound intensity rise and fall with a time of $0\mathrm{.}200$ s between the maximum intensity and the succeeding minimum intensity. What is the difference in frequency of the two sound waves?

Group of answer choices

$5\mathrm{.}00$ Hz

$10\mathrm{.}0$ Hz

$1\mathrm{.}25$ Hz

$2\mathrm{.}50$ Hz

$0\mathrm{.}200$ Hz

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