Ten tuning forks are arranged in increasing order of frequency in such a way that any two nearest tuning forks produce 4 beats/sec. The highest frequency is twice of the lowest. Possible highest and the lowest frequencies are
Using nLast = nFirst + (N – 1)x
where N = Number of tuning fork in series
x = beat frequency between two successive forks
2n = n + (10 – 1) ´ 4 n = 36 Hz
nFirst = 36 Hz and nLast = 2 ´ nFirst = 72 Hz