Build a repeatable problem-solving method
Separate givens, assumptions and the requested quantity before solving.
The idea
A correct calculation begins with a correct model. State the information given, identify the requested quantity and units, then check whether the result is plausible.
A method to try
- Write down the known values and any conditions such as independence or complete dominance.
- Name the quantity requested, including its unit or denominator.
- Choose a rule that connects the known and unknown values.
- Calculate, check the unit and explain why a tempting alternative is wrong.
Follow the reasoning.
A success rate rises from 20% to 30%. What is the relative increase?
- The change is 10 percentage points.
- Use the original rate as the denominator: 10/20 = 0.5.
- Convert to a percentage: 50% relative increase.
Think it through first.
A rate falls from 30% to 20%. What is the relative decrease?
Show the explanation
One third, approximately 33.3%
Now the starting rate is 30%, so the relative decrease is 10/30, not 10/20. Direction changes the baseline.
Make it your own
Choose a missed question and write one sentence describing the decision you would change next time.
This lesson is one part of a short starter pathway. It does not cover the full exam syllabus or establish a predicted score.
Official references
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- CISIA: CEnT-S structure and syllabus (opens in a new tab)Checked 2026-09-20
- CISIA: CEnT rules (opens in a new tab)Checked 2026-09-20
- CISIA: practice simulations (opens in a new tab)Checked 2026-09-20
- Biology 2e: Laws of Inheritance (opens in a new tab)Checked 2026-09-20
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- Biology 2e: The Light-Dependent Reactions of Photosynthesis (opens in a new tab)Checked 2026-09-20
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- College Physics 2e: The Ideal Gas Law (opens in a new tab)Checked 2026-09-20
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- Introductory Statistics 2e: Frequency, Frequency Tables, and Levels of Measurement (opens in a new tab)Checked 2026-09-20
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- Prealgebra 2e: Solve Geometry Applications — Circles and Irregular Figures (opens in a new tab)Checked 2026-09-20
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- Contemporary Mathematics: Truth Tables for the Conditional and Biconditional (opens in a new tab)Checked 2026-09-20
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