Two towers A and B of height 23 m and 11 m respectively, stand 9 m apart. A straight rod is joined to the two tops of the towers. A monkey sitting on the top of A, climbs the rod to reach the top of B. If the monkey takes 5 minutes to reach the other end, what is the average speed of the monkey?

  1. A. 10 m/min
  2. B. 5 m/min
  3. C. 10 cm/sec
  4. D. 5 cm/sec

Correct Answer: D. 5 cm/sec

Explanation

The vertical distance is 23 - 11 = 12 m and horizontal distance is 9 m. Length of the rod = \sqrt{12^2 + 9^2} = 15 m. Speed = 15 \text{ m} / 5 \text{ min} = 3 \text{ m/min}, which is 300 \text{ cm} / 60 \text{ sec} = 5 \text{ cm/sec}.

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