WAEC - Further Mathematics (2023 - No. 24)
Adu's scores in five subjects in an examination are 85, 84, 83, 86 and 87. Calculate the standard deviation.
2.0
1.4
1.8
1.6
Explanation
n = 5
x̄ = \(\frac{∑x}{n} = \frac{85 + 84 + 83 + 86 + 87}{5} = \frac{425}{5} = 85\)
| \(x\) | \(x - x̄\) | \((x - x̄)^2\) |
| 85 | 0 | 0 |
| 84 | -1 | 1 |
| 83 | -2 | 4 |
| 86 | 1 | 1 |
| 87 | 2 | 4 |
| \(\Sigma(x - x̄)^2 = 10\) |
\S.D = \(\sqrt{\frac{∑(x - x̄ )}{n}}\) = \(\sqrt{\frac{10}{5}}\)
∴ S.D = \(\sqrt{2}\) =1.4
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