Inductive Reasoning
What this section tests
Inductive questions ask you to find a pattern and project it forward, or to judge how strongly a set of observations supports a general claim. Unlike deduction, the conclusion is probable, not certain, so the job is to find the best-supported rule.
Concepts to master
- Sequence patterns. Look at differences, then ratios, then alternating sub-sequences (odd positions and even positions each following their own rule).
- Rule confirmation. A rule is only good if it explains every term, not just the last two.
- Generalization strength. Larger, more varied samples support broader conclusions; a single case supports almost nothing; a counterexample refutes a universal claim.
- Trend reading. Recognize growth, decline, cycling, and acceleration from a described set of observations.
Traps
- A rule fitted to the last two numbers only.
- Two patterns that both work for the given terms - check which one the answer choices allow.
- Confusing correlation with a cause; inductive items often test whether you overclaim.
- Overgeneralizing: "all," "always," "never" conclusions drawn from a handful of instances.
Rule of thumb
Test your proposed rule against the first term as well as the last. If it fails anywhere, you have the wrong rule. When two rules work, choose the simpler and the one the choices support.
Worked example
Sequence: 2, 6, 12, 20, 30. Differences: 4, 6, 8, 10 - increasing by two. The rule is "add the next even number," so the following difference is 12 and the next term is 42. Note that the rule also explains the first jumps, which is why it beats "add 4, then 6" guesses. A second way to see it: n(n+1) gives 2, 6, 12, 20, 30 - the same answer from a cleaner rule.