What does Decision Making test?
Logic, interpreting data, evaluating arguments, diagrams, assumptions, probability, and drawing valid conclusions.
What is the golden rule in DM?
Only accept something as true if it is logically guaranteed, not just likely or plausible.
What is the biggest DM trap?
Thinking about what is probable rather than what is certain.
What makes a conclusion valid in syllogisms?
It follows logically from all given statements without extra assumptions.
What two questions should you always ask in DM?
- Must this be true?
- Does the passage guarantee it?
What can you NEVER assume in logic puzzles?
- Real-world logic
- Common sense
- Typical behaviour
Only use the information given.
What does “Some A are B” mean?
At least one A is B — possibly all, but not guaranteed.
What does “No A are B” mean?
Zero overlap — A ∩ B = 0.
What does “All A are B” mean?
The entire group A sits inside group B (A ⊆ B).
What is the rule for diagramming syllogisms?
Quickly draw sets/circles, place restrictions, and check if the conclusion must ALWAYS be true.
Why use Venn diagrams in DM?
To visually check whether a conclusion holds in every possible arrangement.
What does “cannot be true” mean?
There exists no arrangement consistent with the statements where it holds.
What does “could be true” mean?
There is at least one possible arrangement where it holds — not necessarily always.
What is the most important skill for data interpretation?
Extract ONLY the numbers or relationships needed — ignore irrelevant information.
What should you always avoid when reading graphs/tables?
Interpolating, guessing trends, or adding values not shown.
When do you multiply probabilities?
For AND events (both must occur).
What is the best strategy for data questions?
Simplify → identify what is being compared → check each option methodically.
What is probability?
Favourable outcomes ÷ total possible outcomes.
What is the most common DM probability mistake?
Mixing up independent vs dependent events.
When do you add probabilities?
For OR events (one of several possibilities occurs).
What is conditional probability?
Probability of A given B has already occurred — limit sample space to B.
What’s the first step in logic puzzles?
Convert ALL information into a structured format (table, list, grid).
What is the rule for “if… then…” statements?
- If A → B is true
- A happening guarantees B
- B happening does NOT guarantee A
What does “A only if B” mean?
If A is true, B must also be true (A → B).
