Incorrect answer in physics problem (beat frequency)

[duffee]

There is a mathematical error in the following

webwork-open-problem-library/Contrib/BrockPhysics/College_Physics_Urone/16.Oscillatory_Motion_and_Waves/NU_U17-16-10-004.pg

Lines 39 to 40 in 8e5a512

	$A1 = $favg+$fbeat;
	$A2 = $favg-$fbeat;

The beat frequency is the difference between $A1 and $A2, so need to add/subtract half the beat frequency to the average, like so

$A1 = $favg + $fbeat/2;
$A2 = $favg - $fbeat/2;