GCSE · Scatter graphs & correlation

Predicting from a line of best fitExam-style questions

How to read an estimate off a line of best fit in both directions, why a prediction inside the data is trustworthy and one outside it is not, and what the gradient of the line means in the context of the question.

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10 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 1Level 2Level 3Level 4Level 5
  1. 1
    A company owns 13 machines. The scatter graph shows the age of each machine, in years, and the amount spent on repairing it last year. A line of best fit has been drawn.12345678100200300400500age (years)repair cost (£)(a) Find the gradient of the line of best fit.

    (b) Use the line of best fit to estimate the amount spent last year on repairing a machine that is 55 years old.

    (c) Interpret the gradient of the line of best fit in the context of this question.

    (d) The company also owns a machine that is 2020 years old. Explain why the line of best fit should not be used to estimate the amount spent on repairing that machine.
    Level 5 · 6 marksTry it