Scio NSZ OSP flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Analogy relation test

Name a single relation linking the first pair (e.g. part to whole, cause to effect) and check that exactly the same relation fits the second pair in the same direction.

Contrapositive of if–then

From 'if P then Q' the only valid reversal is 'if not Q then not P'. The forms 'if Q then P' and 'if not P then not Q' are invalid.

Meaning of 'only if'

'P only if Q' means P implies Q, so Q is a necessary condition for P. It does not mean Q implies P, which would make Q sufficient.

Meaning of 'unless'

'P unless Q' is equivalent to 'if not Q then P', and also to 'P or Q'. It states that Q is the only exception preventing P.

Scope of 'some'

'Some' asserts that at least one case exists and is compatible with all. It never licenses the conclusion 'most' or 'all' in a verbal inference item.

Odd-one-out criterion

Choose the single property shared by all remaining items and absent from the excluded one. Multiple unrelated similarities between two items are distractors.

Word-in-context method

Insert each candidate option into the original sentence and keep only the word preserving both the literal meaning and the sentence's logical direction and tone.

Two-blank sentence completion

Evaluate each option against both blanks at once. An option that fits one blank but not the other is always wrong, however natural it sounds.

Successive percentage changes

Combine percentage changes by multiplying factors, not adding them: +20% then −15% gives 1.20 × 0.85 = 1.02, a net increase of 2%.

Percentage points versus percent

A change from 20% to 25% is 5 percentage points but a 25% relative increase, since the change is divided by the original 20%.

Weighted combined average

When groups of size n1 and n2 have means m1 and m2, the overall mean is (n1m1 + n2m2)/(n1 + n2), weighted by group size, not a plain average of means.

Combined work rate

Individual rates add: if one worker finishes in a hours and another in b hours, working together they finish in ab/(a + b) hours.

Average speed over equal distances

For two equal-length legs at speeds v1 and v2, average speed is the harmonic mean 2v1v2/(v1 + v2), always less than the arithmetic mean.

Compound versus simple interest

Simple interest is P·r·t; compound interest is P(1 + r)^t − P. Compound exceeds simple whenever t > 1 and r > 0, because interest earns interest.

Ratio part from total

If a : b = 3 : 5, the parts are 3k and 5k and the total is 8k, so one part equals its share divided by the sum of shares times the total.

Number-series check order

Test differences first, then ratios, then alternating subsequences, then squares, cubes or ±n patterns. Apply the simplest rule that fits all given terms.

Reverse percentage problem

If a price after a 20% rise is 120, the original is 120 / 1.20 = 100. Divide by the multiplier; never subtract 20% from the final value.

Ordering clue to inequality

Translate 'A is before B' into A < B and chain transitive relations into one sequence. Then discard any option that violates a single link.

Elimination by strictest clue

Apply the most restrictive clue first, since it removes the most options. Discard every option violating any clue before comparing the survivors.

Exclusion clue scope

'X and Y are never together' forbids exactly the pairing of X with Y. It does not forbid X from joining other members of that group.

Permutation count

The number of ways to arrange all n distinct items in a row is n!. To choose and order k of n items, use n!/(n − k)!.

Combination count

The number of unordered selections of k items from n is n!/(k!(n − k)!). Use it when the order of chosen items does not matter.

Grid method for puzzles

Draw one row per position or person and mark confirmed and excluded entries. A completed row or column forces the remaining assignments.

Hypothetical testing in puzzles

When clues do not force an arrangement, temporarily assume one option and propagate it. Contradiction eliminates the option; consistency keeps it as possible.

Conclusion identification

The conclusion is the claim the author wants accepted; premises are the evidence supporting it. Indicator words include therefore, thus, so and consequently.

Necessary assumption test

The correct assumption is required by the argument: negate it and the conclusion no longer follows. An assumption already stated in the text is not the answer.

Correlation versus causation

Two variables moving together does not prove one causes the other. Alternatives are reversed causation, a shared common cause, or coincidence and selection bias.

Necessary versus sufficient

A is necessary for B when B implies A. A is sufficient for B when A implies B. Confusing the two directions is a standard flaw in arguments.

Hasty generalization

A flaw that draws a broad conclusion from a small or unrepresentative sample, such as inferring a national trend from a handful of cases.

False dilemma

A flaw that presents only two options when more exist, forcing a choice between extremes and ignoring intermediate or alternative possibilities.

Strengthen versus weaken

A strengthening option makes the conclusion more likely given the premises; a weakening option makes it less likely. Both must affect the evidence-to-conclusion link.

Retrieval practice

Recalling material from memory through self-testing strengthens retention more than rereading. Spacing these tests over time improves long-term recall.