GR-1.3 Aptitude: logical reasoning

What this is and why it exists

Reasoning questions look unfamiliar the first time and are almost entirely pattern recognition. The second time you meet a seating-arrangement puzzle it is not a puzzle any more, it is a procedure you have run before.

That is the whole shape of this topic. Each family of question has a fixed method. Learn the method once, make it automatic, then mix the families under a clock. Switching between methods at speed is a separate skill from knowing them.

As with the arithmetic paper, the practice bank is external and free. What is supplied here is the order, the hours, and the habit of naming what you are doing before you do it.

The vocabulary

• Series — a sequence of numbers or letters built by a hidden rule, which you name and continue.
• Coding and decoding — a substitution rule applied to letters or digits, recovered from examples.
• Blood relations — relationship puzzles solved with a drawn family tree.
• Direction sense — movement problems solved with a sketched compass.
• Seating arrangement — people placed in a line or circle under constraints.
• Syllogism — statements from which you decide what follows logically, regardless of whether it is true.
• Family — one type of question with one fixed procedure.

The mental model

Every family here has a procedure, and each procedure has a physical form on paper. Coding and decoding is a substitution table. Blood relations is a family tree. Direction sense is a compass sketch. Seating is a diagram. The single largest improvement most people make is deciding to draw the thing instead of holding it in their head.

Series questions come first because they reward one habit more than any other: naming the pattern before choosing an answer. Say it out loud or write it down — *each term adds three more than the last*, *every second letter moves back two*. Naming it is what separates reasoning from guessing, and on series questions the pattern is the entire question.

Coding, blood relations and direction sense are three families with three fixed procedures, and each takes about one set to learn. After that they stop being problems. Do not spend a week on them.

Seating arrangements and puzzles are the family students fear, and they are the one that most rewards a diagram. Work five slowly with a diagram, then five against the clock. The slow five build the habit; the timed five show you how much time the diagram actually saves, which is more than anyone expects.

Syllogisms are the odd family out, because common sense is the wrong tool. The question is about what follows from the statements, not about what is true in the world. A conclusion can be plainly true and still not follow. That is the trap the questions are built around. Writing the rule you used for each answer is what keeps logic and knowledge apart.

Then mix them. The paper does not serve one family at a time. Moving between four procedures under time is its own skill, and it never appears while you practise families separately. A mixed twenty-five in twenty-five minutes is the real rehearsal.

Carry the error log over from the arithmetic. Reasoning errors cluster more tightly than arithmetic ones — usually one family, and usually one misread instruction inside it.

What you should now be able to explain or do

Name the pattern in a number or letter series before answering. Build a substitution table for a coding question, a family tree for a relations question, and a compass sketch for a direction question. Do it without thinking about which to use. Solve a seating arrangement with a diagram, under time. Say why a conclusion can be true and still not follow. Work a mixed twenty-five-question set in twenty-five minutes, and add every miss to the log with its family and its reason.

Check yourself