JDF Recruit Assessment cheat sheet

A valid syllogism conclusion must follow from the premises alone; reject any conclusion that requires an unstated assumption.

'Some A are B' does not imply 'some A are not B'; the possibility of 'all A are B' remains open.

Contrapositive is logically equivalent to the original: 'if P then Q' equals 'if not Q then not P'.

Converse ('if Q then P') and inverse ('if not P then not Q') are NOT equivalent to the original conditional.

'Necessary' condition = cannot occur without it; 'sufficient' condition = guarantees the outcome; they are not interchangeable.

Analogy items test the same relationship type: part-to-whole, cause-to-effect, function, degree, or category membership.

For word-meaning items, substitute each option into the sentence and keep the one preserving the original logic.

A passage's main conclusion is the claim supported by the rest; other sentences are evidence, restatement, or background.

Percentage change = (new − old) ÷ old × 100; a 20% rise then 20% fall leaves 96% of the original value.

Speed = distance ÷ time; convert km/h to m/s by multiplying by 5/18 (e.g., 36 km/h = 10 m/s).

Compound growth: final = start × (1 + r)^n; simple growth: final = start × (1 + rn).

Average (mean) = sum of values ÷ count; if every value rises by k, the mean rises by k.

Ratio scaling: divide a total by the sum of ratio parts, then multiply by each part.

Work rate: combined rate = 1/a + 1/b; time together = ab ÷ (a + b) for two workers.

Profit or loss percentage is calculated on cost price unless the question states otherwise.

Estimate first by rounding to one significant figure to eliminate implausible answer options quickly.

Lever: effort × effort arm = load × load arm; a longer effort arm reduces required force.

Class 1 lever has the fulcrum between effort and load; class 2 has load between fulcrum and effort; class 3 has effort between fulcrum and load.

Mechanical advantage = load ÷ effort; velocity ratio = effort distance ÷ load distance.

Fixed pulley changes direction only (MA = 1); a movable pulley halves the effort (MA = 2).

Gear ratio = teeth on driven gear ÷ teeth on driver gear; meshed gears turn in opposite directions.

Pressure = force ÷ area; the same force over a smaller area produces greater pressure.

In a fluid, pressure increases with depth; objects float when buoyancy equals their weight.

Density = mass ÷ volume; an object denser than the fluid it sits in will sink.

Work = force × distance moved in the direction of the force; holding a load still does no work.

A cube has 6 faces, 12 edges, and 8 vertices; a net must contain exactly 6 squares that fold without overlap.

Rotating a shape preserves size and angles; reflecting it reverses orientation (handedness).

Two reflections across parallel lines equal one translation of twice the gap between the lines.

A shape has rotational symmetry of order n if it maps onto itself n times in a full 360° turn.

Lines of symmetry: a square has 4, a rectangle 2, an equilateral triangle 3, a circle infinitely many.

When folding and punching paper, each fold doubles the number of holes; mirror the punch across every fold line.

Top, front, and side views each show only two of the three dimensions; match projections to eliminate options.

Clockwise and anticlockwise quarter turns of 90° map north to east and north to west respectively.

The UK Parliament has two chambers: the elected House of Commons and the appointed House of Lords.

The United Nations has 193 member states; its Security Council has 5 permanent and 10 elected members.

NATO is a collective-defence alliance founded in 1949; Article 5 treats an attack on one member as an attack on all.

The UK is a constitutional monarchy with a parliamentary democracy; general elections are held at least every 5 years.

The Commonwealth is a voluntary association of 56 member states, most with historic links to the British Empire.

The Prime Minister leads the government and is normally the leader of the party with a Commons majority.

The Geneva Conventions set rules of armed conflict, including protection of civilians and prisoners of war.

Currency, capital, and leader questions are best answered by matching the country to its region first.

BMI = mass (kg) ÷ height (m)²; a value of 18.5–24.9 is classed as healthy weight for adults.

Pace = time ÷ distance; a 2.4 km run in 12 minutes equals 5 minutes per kilometre.

Target heart rate ≈ (220 − age) × 0.6 to 0.8 for moderate-to-vigorous aerobic training.

A shuttle run tests agility via rapid direction changes; lower times indicate faster change of direction.

A press-up measures upper-body muscular endurance; a sit-up or plank measures core endurance.

The bleep (multi-stage fitness) test estimates VO2 max from the level reached before voluntary exhaustion.

Warm-up raises muscle temperature and reduces injury risk; cool-down aids recovery and gradual heart-rate return.

Agility combines speed, balance, coordination, and reaction time rather than raw strength alone.

'Neither...nor' and 'either...or' pairings must stay consistent within a sentence.

An assumption is an unstated premise the argument depends on; a weakener attacks it, a strengthener supports it.

Inference questions accept only what must be true, not what is merely likely or plausible.

Odd-one-out items: identify the shared property of all but one item, then confirm the excluded item lacks it.

Watch for absolute words (all, never, only) in options; they are usually wrong unless the passage states them.

Restatement options repeat the passage without answering the question stem; eliminate them first.

A cause must precede an effect in time; correlation alone does not establish causation.

When comparing two passages, note agreement on fact versus disagreement on interpretation or emphasis.

To find an original value after a percentage change, divide by (1 ± change): 120 after +20% came from 120 ÷ 1.2 = 100.

Simple interest = principal × rate × time; compound interest grows on accumulated interest too.

Unit conversions: 1 km = 1000 m, 1 hour = 3600 s, 1 kg = 1000 g, 1 litre = 1000 mL.

Distance = speed × time; for two objects moving toward each other, add their speeds.

Percentage of a number = (percent ÷ 100) × number; 'of' signals multiplication.

A fraction converts to a percentage by multiplying by 100; 3/8 = 37.5%.

Median is the middle value of an ordered list; with an even count, average the two middle values.

Check answers by reverse calculation or by testing whether the result satisfies the original condition.