A number of tuning forks are arranged in the order of increasing frequencies and any two successive tuning forks produce 4 beats/second, when sounded together. If the frequency of the last tuning fork is the octave of the first tuning fork and if the frequency of the first tuning fork is 256 Hz, then the number of tuning forks is

Options

A. 46
B. 60
C. 65
D. 30

Answer

C

Explanation

`2x = x + (n -1)d " " :. x = (n -1) xx 4`
`(256)/(4) = n -1 " " :. 64 = n-1 " " :. n = 65`