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WAEC Mathematics 2021 Question 14

Question 14

Variation

Given that R is directly proportional to L and inversely proportional to P, R = 3 when L = 9 and P = 0.8, find R when L = 15 and P = 1.8.

  1. A.2.2
  2. B.3.3
  3. C.6.6
  4. D.0.3
Show the answer and explanation

Answer: A (2.2)

Explanation

R = kL/P: 3 = 9k/0.8 so k = 0.8/3. Then R = (0.8/3) × 15/1.8 ≈ 2.2.