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JAMB Mathematics 2004 Question 15

Question 15

Variation

The length L of a simple pendulum varies directly as the square of its period T. If a pendulum with period 4 sec. is 64cm long, find the length of a pendulum whose period is 9 sec.

  1. A.36cm
  2. B.96cm
  3. C.144cm
  4. D.324cm
Show the answer and explanation

Answer: D (324cm)

Explanation

L = kT2: 64 = 16k, so k = 4. Then L = 4 × 81 = 324cm.