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Calculate the standard deviation of the following data: 7, 8, 9, 10, 11, 12, 13.

Mathematics
JAMB 1993

Calculate the standard deviation of the following data: 7, 8, 9, 10, 11, 12, 13.
  • A. 2
  • B. 4
  • C. 10
  • D. 11
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Correct Answer: Option A
Explanation
\(\begin{array}{c|c} x & x - x & (x - x)^2\\ \hline 7 & -3 & 9\\8 & -2 & 4 \\9 & -1 & 1\\10 & 0 & 1\\11 & 1 & 1\\ 12 & 2 & 4\\13 & 3 & 9\\ \hline & & 28\end{array}\)

S.D = \(\sqrt{\frac{\sum(x - x)^2}{N}}\)

= \(\sqrt{\frac{\sum d^2}{N}}\)

= \(\sqrt{\frac{28}{7}}\)

= \(\sqrt{4}\)

= 2

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