Calculate, correct to one decimal place, the standard deviation of the numbers: -1, 5, 0,
FURTHER MATHEMATICS
WAEC 2007
Calculate, correct to one decimal place, the standard deviation of the numbers: -1, 5, 0, 2 and 9.
- A. 7.2
- B. 6.6
- C. 3.6
- D. 3.2
Correct Answer: C. 3.6
Explanation
| \(x\) | -1 | 5 | 0 | 2 | 9 | Total = 15 |
| \(x - \bar {x}\) | -4 | 2 | -3 | -1 | 6 | |
| \((x - \bar{x})^{2}\) | 16 | 4 | 9 | 1 | 36 | 66 |
Mean = \(\frac{15}{5} = 3\)
SD = \(\sqrt{\frac{\sum (x - \bar {x})^{2}}{n}}\)
= \(\sqrt{\frac{66}{5}} \)
= \(\sqrt{13.2}\)
= 3.6
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