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WAEC Further Mathematics 2014 Question 28

Question 28

Statistics

The deviations from the mean of a set of numbers are (k + 3)2, (k + 7), −2, k and (k + 2)2, where k is a constant. Find the value of k.

  1. A.3
  2. B.2
  3. C.−2
  4. D.−3
Show the answer and explanation

Answer: D (−3)

Explanation

Deviations from the mean add up to 0: 2k² + 12k + 18 = 0, i.e. (k + 3)² = 0, so k = −3.