AOSB Aptitude flashcards

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

Valid vs sound argument

An argument is valid when the conclusion must follow from the premises; it is sound only when it is valid and all its premises are actually true.

Necessary condition

A condition that must hold for the claim to be true; without it the claim fails, but it may not be enough on its own.

Sufficient condition

A condition whose presence guarantees the claim is true, though the claim might also be true through other routes.

Quantifier scope

The range a word like all, most, some or none covers; 'most' means more than half but not all, and scope changes what follows.

Assumption in arguments

An unstated premise the argument needs for its conclusion to follow; negating it should break the reasoning.

Falsifiability

A claim is falsifiable when some possible observation could show it to be false; unfalsifiable claims cannot be tested against evidence.

Successive percentage change

Percentage changes multiply rather than add: a 10% rise then a 10% fall gives 1.10 × 0.90 = 0.99, a net 1% loss.

Average speed two equal distances

When equal distances are covered at speeds a and b, average speed is 2ab/(a+b), the harmonic mean, not the arithmetic mean.

Combined work rate

Rates add: if A alone takes a days and B alone takes b days, working together they finish in ab/(a+b) days.

Compound interest formula

Amount after n periods is P(1 + r)^n, where P is the principal and r the interest rate per period as a decimal.

Ratio sharing rule

To split a total in a given ratio, divide the total by the sum of the ratio parts, then multiply by each part.

Independent event probability

For independent events the probability both occur is the product of their individual probabilities; for mutually exclusive events it is the sum.

Percentage change formula

Percentage change equals (new value − old value) divided by old value, multiplied by 100; the denominator is always the original.

Rotation versus reflection

Rotation is rigid and preserves orientation; reflection reverses orientation, so a reflected shape cannot be rotated back into the original.

Alternating sequence rule

In a series where odd and even positions follow different patterns, analyse the two interleaved subsequences separately before combining.

Cube net opposite faces

On a cube net, faces separated by exactly one face in a straight line are opposite; opposite faces never share an edge.

Regions cut by lines

With n straight lines in general position, no two parallel and no three concurrent, the maximum number of regions is n(n+1)/2 + 1.

Mirror image properties

A mirror image swaps left and right while preserving top and bottom order; a 180-degree rotation swaps both axes instead.

Counting attributes rule

Common abstract-series rules count sides, vertices, enclosed regions, intersections or line segments, often changing by a constant step.

Critical path

The longest chain of dependent tasks through a project network; its length sets the minimum possible project duration.

Float in scheduling

Total float is latest start minus earliest start; a task with zero float lies on the critical path and any delay slips the project.

Binding constraint

The step with least capacity that limits overall throughput; improving any non-bottleneck step does not raise total output.

Three-point estimate

Expected duration equals (optimistic + 4 × most likely + pessimistic) divided by 6, weighting the likely case most heavily.

Resource levelling

Rescheduling tasks within their float to smooth peaks in demand for people or equipment, usually at the cost of a longer duration.

Urgency versus importance

Prioritise tasks by both urgency, how soon due, and importance, impact on objectives; blocking tasks outrank isolated ones.

Backward planning

Start from the deadline and work back through task durations to test whether the plan is achievable before committing resources.

Leaderless group scoring

Assessors score contribution to the team outcome, including drawing out others and summarising agreement, not dominance or airtime.

Explicit role allocation

Assigning timekeeper, scribe and presenter early prevents duplicated effort and ensures the group covers all required outputs.

Testing agreement aloud

Summarising the emerging consensus and asking whether anyone objects converts discussion into a recorded decision the group can act on.

Command task sequence

Confirm the brief, plan briefly, brief the team on roles, then supervise progress and adjust when conditions change.

STAR answer structure

Situation, Task, Action, Result: describe context, your responsibility, what you specifically did, and the concrete outcome.

Weakness answer pattern

Name a genuine weakness, then state the specific corrective action taken and the observable improvement, avoiding disguised strengths.