VCE · Topic explainer
What is extrapolation in General Mathematics?
Extrapolation uses a model to predict a value beyond the range of the observed inputs. Interpolation predicts within that range. A calculation can be correct even when the extrapolated prediction is unreliable, because the relationship observed in the data may change outside the measured interval.
Worked example
A garden club models plant height using observations from weeks 2 to 6. Using the model at week 4 is interpolation. Using it at week 8 is extrapolation because 8 is larger than the largest observed input.
If the fitted model is height = 3 × week + 4 cm, the predicted height at week 8 is 28 cm. Qualify the prediction by saying the model assumes the same growth rate continues beyond week 6. Growth could slow as the plant matures.
Official exam practice
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