Answer:
557 Hz
Explanation:
The concepts needed to solve this question are the number of beats formed per second by two frequencies and the frequency of the vibrating string's vibrations.
Given that:
Actual frequency f= 551 Hz
Beat frequency Δf = 6
In as much as the tension is increased, its frequency will also increase
Thus; the new frequency of tightened string f' = f + Δf
f' = 551 Hz + 6 /s
f' = 551Hz + 6/s ( 1 Hz/s)
f' = 557 Hz