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WAEC Mathematics 2012 Question 27

Question 27

Measures of Dispersion

Given that the mean of the scores 15, 21, 17, 26, 18 and 29 is 21, calculate the standard deviation of the scores.

  1. A.√10
  2. B.4
  3. C.5
  4. D.√30
Show the answer and explanation

Answer: C (5)

Explanation

Squared deviations from 21: 36, 0, 16, 25, 9, 64, total 150. Variance = 150/6 = 25, so SD = 5.