In a guitar, two strings A and B made of same
material are slightly out of tune and produce beats
of frequency 6 Hz. When tension in B is slightly
decreased, the beat frequency increases to 7 Hz.
If the frequency of A is 530 Hz, the original
frequency of B will be :
(1) 523 Hz
(2) 524 Hz
(3) 536 Hz
(4) 537 Hz