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JAMB Mathematics 1998 Question 45

Question 45

Measures of Dispersion

Find the positive value of x if the standard deviation of the numbers 1, x + 1, 2x + 1 is √6

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

Answer: C (3)

Explanation

The mean is x + 1 and the deviations are −x, 0, x. Variance = 2x²/3 = 6, so x² = 9 and x = 3.