Calculate the standard deviation of 30, 29, 25, 28, 32 and 24.
FURTHER MATHEMATICS
WAEC 2018
Calculate the standard deviation of 30, 29, 25, 28, 32 and 24.
- A. 2.0
- B. 2.8
- C. 3.0
- D. 3.2
Correct Answer: B. 2.8
Explanation
| \(x\) | \(x - \mu\) | \((x - \mu)^{2}\) |
| 24 | -4 | 16 |
| 25 | -3 | 9 |
| 28 | 0 | 0 |
| 29 | 1 | 1 |
| 30 | 2 | 4 |
| 32 | 4 | 16 |
| \(\sum\) = 168 | 46 |
\(\mu = \frac{24+25+28+29+30+32}{6} = \frac{168}{8} = 28\)
\(S.D = \sqrt{\frac{\sum{(x - \mu)^{2}}}{n}} = \sqrt{\frac{46}{6}}\)
= \(\sqrt{7.67} \approxeq 2.8\)
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