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CAIE A-Level Economics 2.3.3 PES Coefficient

Practise interpreting PES coefficients and supply-curve geometry, including unitary, perfectly elastic and perfectly inelastic supply at different points on a curve.

Syllabus
2026–2028
Course
Economics 9708
Level
AS

Exam points

  • classify PES above one as elastic, below one as inelastic and equal to one as unitary
  • recognise vertical supply as perfectly inelastic and horizontal supply as perfectly elastic
  • interpret how PES can vary along a straight supply curve after a price or tax change

2.3.3—PES coefficient question 1

[Maximum number: 8]

The price elasticity of supply (PES) for a new smartphone is estimated to be 0.8 in the short run and 1.8 in the long run.

Explain what these estimates mean for producers and consumers of smartphones and consider why the estimates differ.

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