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JAMB Mathematics 2000 Question 42

Question 42

Measures of Dispersion

If the mean of the numbers 0, x + 2, 3x + 6 and 4x + 8 is 4, find their mean deviation.

  1. A.0
  2. B.2
  3. C.3
  4. D.4
Show the answer and explanation

Answer: C (3)

Explanation

The mean is (8x + 16)/4 = 2x + 4 = 4, so x = 0 and the numbers are 0, 2, 6, 8. Their distances from 4 are 4, 2, 2, 4, whose average is 3.