Calculate in IB Economics

What your response needs

Formula → substitution → answer → brief interpretation when useful.

• Correct formula
• Substitution and working
• Final value with appropriate unit or sign

A worked economics example

Question: Calculate PED when price rises by 10% and quantity demanded falls by 20%.

An incomplete response: PED is elastic.

A more complete response:

PED = %ΔQd ÷ %ΔP

PED = −20% ÷ 10% = −2

The absolute value is 2, so demand is price elastic.

Common mistakes to avoid

• Providing only the final number
• Inverting the formula
• Omitting the unit, sign or interpretation

Try it yourself

Read the question and its mark allocation before deciding how much detail to include. A response structure helps you organise your answer; it is not a script to memorise.

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About this guidance

These explanations and examples are original Econograms study guidance. They are not official IB questions or markschemes, and Econograms is not endorsed by the International Baccalaureate. Follow the wording and requirements of the question set by your teacher or examination.