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WAEC Mathematics 2020 Question 16

Question 16

Variation

Given that x is directly proportional to y and inversely proportional to Z, x = 15 when y = 10 and Z = 4, find the equation connecting x, y and Z.

  1. A.x = 6y/Z
  2. B.x = 12y/Z
  3. C.x = 3y/Z
  4. D.x = 3y/(2Z)
Show the answer and explanation

Answer: A (x = 6y/Z)

Explanation

x = ky/Z. Then 15 = 10k/4, so k = 6 and x = 6y/Z.