16 tunning forks are arranged in the order of increasing frequencies. Any two successive forks give 8 beats per sec when sounded together. If the frequency of the last fork is twice the first, then the frequency of the first fork is 

(1) 120

(2) 160

(3) 180

(4) 220

(1) Using nLast = nFirst + (N – 1)x

⇒ 2n = n + (16 – 1) × 8 ⇒ n = 120 Hz

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