42.6 is the answer I believe because you would do 2,560 divided by 60 if I'm correct.
Answer:
346.66 Hz
Explanation:
= Length of string which is unfingered = l
= Length of string which is vibrate when fingered = 
= Unfingered frequency = 260 Hz
= Fingered frequency
Frequency is inversely proportional to length

So,

The frequency of the fingered string is 346.66 Hz
Answer:
option 1 will be the answer.
Explanation:
hope it helps.