Calculate the variance of 2, 3, 3, 4, 5, 5, 5, 7, 7 and 9

  • A 2.2
  • B 3.4
  • C 4.0
  • D 4.2
waec 2017mathematics

The correct answer is D. 4.2

x = \(\frac{2 + 3 + 3 + 4 + 5 + 5+ 5+ 7 + 7 + 9}{10}\)

=\(\frac{50}{10}\)

= 5

Variance = \(\frac{\sum{(x - x})^2}{N}\)

\(\frac{9 + 4+ 4+ 1 + 4 + 4 + 16}{10}\)

= \(\frac{42}{10}\)

= 4.2

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