Answer:
her initial frequency is 788 Hz
Explanation:
Given;
beat frequency, Fb = 4 Hz
frequency of turning fork, F1 = 784 Hz
frequency of the flute, or her initial frequency, F2 = ?
Beat frequency is always equal to the difference in frequency of the two notes that interfere to produce the beats. In this case, to determine the frequency of the flute, which is her initial frequency, we apply this formula for beat frequency;
Fb = F2 - F1
4 = F2 - 784
F2 = 4 + 784
f2 = 788 Hz
Therefore, her initial frequency is 788 Hz