WAEC Mathematics 2012 Objective — Question 27
Question 27 of 50 from the West African Examinations Council (WAEC) Mathematics 2012 Objective paper, with the correct answer and a full explanation.
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Given that the mean of the scores 15, 21, 17, 26, 18 and 29 is 21. Calculate the standard deviation of the scores.
- A. √10
- B. 4
- C. 5Correct
- D. √30
Explanation
Standard deviation = √(Σ(x−x̄)²/n) = √[((15−21)²+(21−21)²+(17−21)²+(26−21)²+(18−21)²+(29−21)²)/6] = √[(36+0+16+25+9+64)/6] = √(150/6) = √25 = 5.
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