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.
Interpolation and Extrapolation
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.
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.