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A set of heights is measured in centimetres. In which units is its variance given?
AOrdinary centimetres
BCubic centimetres
CSquared millimetres
DSquared centimetres
Answer & Solution
Correct answer: D. Squared centimetres
1. Variance is the average squared distance between the mean and each data value.
2. Every term in that sum is squared, so the units are squared as well.
3. Heights measured in centimetres therefore give a variance in squared centimetres.
4. That is why variance cannot be compared directly with the mean or with the data.
5. The standard deviation is used instead, because it carries the same units as the data.
_Source: Siyavula Mathematics Grade 11 (Everything Maths, CC BY 4.0), Chapter 11: Statistics_
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