Hello, future freshmen!

Welcome to this study guide for TGAT2 Critical & Logical Thinking, specifically the Reasoning Ability (ความสามารถทางเหตุผล) section. In the official TGAT2 blueprint, Reasoning Ability comprises four core sub-types: Figure Series, Figural Analogy, Drawing Conclusions, and Statement Analysis.

In this chapter, we will walk through each of these four areas step-by-step so you understand how to spot patterns, evaluate logical entailments, and systematically eliminate trap options. If it feels challenging at first, don't worry! Let's break it down together.

1. Figure Series (อนุกรมภาพ)

Figure series items require you to deduce the underlying rule governing an ordered sequence of images and choose the figure that logically completes the sequence.

Core Observation Principles:

1. Element Count & Addition/Subtraction: Count shapes, line segments, dots, or petals across consecutive steps (e.g., 3 sides, 4 sides, 5 sides, ...).
2. Rotation & Orientation: Track whether an element rotates clockwise or counter-clockwise, and by what angle (e.g., 45°, 90°, or 180°).
3. Shading & Fill Alterations: Watch how shading moves through zones or alternates between solid, striped, and clear.
4. Positional Shifts: An inner element may step along a grid, corner by corner, or reflect across an axis.

Strategy Tip:

Isolate one feature at a time. When a figure contains multiple moving parts, focus on one specific marker (such as a black dot or arrow). Trace its movement across all frames to eliminate options before checking secondary features.

2. Figural Analogy (อุปมาอุปไมยภาพ)

Figural analogy tests your ability to identify the precise structural transformation between an initial pair of figures ( Figure A : Figure B ) and apply the identical rule to complete the second pair ( Figure C : ? ).

Common Transformational Rules:

  • Inversion / Reflection: Flipping vertically or horizontally across a mirror plane.
  • Nesting & Shape Swap: The outer shape becomes the inner shape, or shading moves from the inside to the outside container.
  • Geometric Mutation: Increasing the number of vertices by one (e.g., triangle becomes quadrilateral) or dissecting a solid shape into outline parts.
  • Superposition & Deletion: Overlapping two figures or removing shared lines while keeping unshared lines.
Strategy Tip:

State the rule clearly in words before checking the answers: "Figure A was rotated 90° clockwise, and its interior circle was filled." Then apply that exact dual-step rule to Figure C.

3. Drawing Conclusions (สรุปความ)

This sub-type tests formal deductive and inductive reasoning. You must determine which conclusion validly follows strictly from the given premises. You must never rely on personal opinion, unstated assumptions, or external world facts.

Common Logical Forms:

1. Conditional Statements ("If... then..."):
- Premise: If it rains, the ground becomes wet.
- Affirmed antecedent: It is raining → The ground is wet (Valid).
- Denied consequent: The ground is not wet → It did not rain (Valid).
- Fallacy warning: The ground is wet does not prove it rained (the ground could be wet from a sprinkler).

2. Categorical Statements ("All / Some / None"): Use Euler circles or Venn diagrams to test inclusion.
- All members of Club X are university students.
- Somchai is a member of Club X.
- Valid Conclusion: Somchai is a university student.

Recognising Non-Inference:

Be prepared for questions where no valid conclusion follows. If the premises allow multiple incompatible arrangements, do not force an inference.

4. Statement Analysis (วิเคราะห์ข้อความ)

Statement analysis involves evaluating short informational conditions, relational puzzles, or prose passages to determine what must be true, what is false, or what cannot be determined.

Systematic Steps to Solve:

1. Construct a Grid or Linear Diagram: Map out ordered positions (e.g., seating order 1 to 5) or characteristic tables (person, department, assigned task).
2. Pin Definite Constraints First: Anchor facts that have only one interpretation (e.g., "A sits on the leftmost seat").
3. Layer Conditional and Negative Rules: Translate negative cues (e.g., "B cannot sit next to C") onto your diagram to restrict open possibilities.
4. Check Remaining Degrees of Freedom: If two variables can swap without violating any condition, an option asserting one fixed state over the other is unproven.

Key Takeaways

  • Figure Series: Track one component at a time (rotation, count, shading) to eliminate options systematically.
  • Figural Analogy: Formulate the transformation rule of the first pair in words, then apply that exact rule to the target.
  • Drawing Conclusions: Rely solely on the provided premises; beware of affirming the consequent or assuming unstated facts.
  • Statement Analysis: Always sketch a table or diagram for condition-based questions before selecting your answer.

Remember that TGAT2 reasoning is entirely about consistency and method. Keep your focus sharp, stay objective, and work systematically! ✌️