A student tunes his guitar by striking a 120 Hertz with a tuning fork, and simultaneously plays the `4^(th)` string on his guitar. By keen observation, he hears the amplitude of the combined sound oscillating thrice per second. Which of the following frequency is the most likely the frequency of the `4^(th)` string on his guitar ?

Options

A. 130
B. 117
C. 110
D. 120

Answer

B

Explanation

Frequency of the fourth string can be derived from harmonic series generated by the strings.
Frequencies of first 4 strings are 120,119,118,117 Hz
`f_(4)=117 Hz`