NZDF aptitude questions: one worked example per reasoning type

A numerical ability example

A vehicle uses 8.4 litres per 100 km. How much fuel is needed for a 350 km move?

The method: set the relationship up before calculating. 8.4 litres per 100 km means 0.084 litres per km, so 350 km needs 29.4 litres. The common error is dividing when you should multiply, which an estimate catches instantly: 350 km is three and a half hundreds, so the answer must be around three and a half times 8.4.

Estimate first, calculate second. It eliminates wrong options faster than arithmetic does.

An inductive reasoning example

A sequence of tiles: each has a number of dots and a shape that rotates. What comes next?

The method: check one attribute at a time across the entire sequence. Count the dots first and write the numbers down. Then track rotation separately. Then shading. Two simple rules running in parallel look like one impossible rule if you try to see them at once, that is the whole difficulty of inductive items.

A fixed order helps more than it sounds: count, position, rotation, shading, size. Working the same order every time means you never lose your place, and it turns an item that felt like insight into one that feels like a checklist.

A deductive reasoning example

All members of the section carry a radio. Some members of the section are trained in first aid. Does it follow that some radio carriers are trained in first aid?

Yes, and the reason is worth being precise about. Every section member carries a radio, so the first-aid-trained members are among the radio carriers. The method: work only from what is stated. Deductive items are almost always failed by importing a real-world assumption the question did not give you.

Watch for the two words that decide most of these: all and some. A conclusion using *all* needs every premise to support it; a conclusion using *some* needs only one case to exist. Reading past that distinction is the single most common error in this section.

A mechanical reasoning example

Two gears mesh directly. The first turns clockwise. Which way does the second turn?

Anticlockwise: directly meshed gears turn in opposite directions. In a train of three, the first and third turn the same way.

The method: learn the handful of principles that generate most mechanical items. Most questions are one of these in a new costume.

What is the difference between inductive and deductive reasoning?

The two feel similar and reward opposite habits. Inductive rewards looking for structure that is not stated; deductive punishes exactly that. Knowing which one you are in before you start is worth a mark or two on its own.

How should you practise each area?

Untimed method work first, then time pressure. Trying to get fast before you are consistent just entrenches whichever approach you happened to start with.

Weight your time toward mechanical reasoning if you have not worked with machinery, and toward inductive if you have been out of formal study for a while. Both are unfamiliarity problems rather than ability problems, which is why they respond so well to a fortnight of short sessions.

Mechanical reasoning is not unique to NZDF, either. Firefighter selection assesses the same principles under the name mechanical comprehension, so the FENZ preparation guide is useful practice for this section even if you are not applying there.

Why does this matter more than a pass?

Because the result feeds trade matching rather than a single threshold, so improving a weak area does not just help you continue, it changes what you can apply for. That logic is set out in the NZDF aptitude test guide, which is the place to start if you have not read it.