Once a line of best fit or linear model is established, it can be used to make predictions.
- Interpolation: predicting a value WITHIN the range of the data — more reliable
- Extrapolation: predicting a value OUTSIDE the range of the data — less reliable, because the trend may not continue
For exam questions: if asked whether a prediction is reliable, state whether it uses interpolation or extrapolation and explain why extrapolation may be unreliable.
This deep dive covers Interpolation and Extrapolation within Linear Graphs Problems for GCSE Mathematics. Revise Linear Graphs Problems in Graphs for GCSE Mathematics with 16 exam-style questions and 11 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 6 of 10 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Linear Graphs Problems
A taxi company charges a fixed fee plus an amount per mile. On a cost graph (£ against miles), what does the y-intercept represent?
A plumber charges according to the formula C = 40t + 30, where C is the total cost in pounds and t is the time in hours. Explain what the values 40 and 30 represent in this context.