Hello, future freshmen!

Welcome to this study guide for TGAT2 Critical Thinking, specifically the "Logical Reasoning" section. I know that for many, hearing the words "reasoning" or "logic" might sound headache-inducing. But believe it or not, these are skills you use in your everyday life—the exam just organizes them into a more systematic format.

In this chapter, we will learn how to identify relationships, draw conclusions from data, and solve problems step-by-step. If you grasp the principles and a few small techniques, scoring well in this section isn't hard at all. If it feels tough at first, don't worry! Let's walk through it together!

1. Numerical Series

This section is all about finding the relationship between a sequence of numbers to determine the next one. The key is to "figure out how the numbers increase or decrease."

Observation Techniques:

1. Addition/Subtraction: The numbers increase or decrease slowly and steadily, or perhaps in a consistent pattern (e.g., +2, +4, +6, ...)
2. Multiplication/Division: The numbers jump or drop very quickly.
3. Interleaved Series (Mixed Series): There are multiple sets of numbers mixed together. Try looking at every other number!

Example: \( 2, 5, 10, 17, 26, ... \)
Method: Look at the differences.
2 to 5 is \(+3\)
5 to 10 is \(+5\)
10 to 17 is \(+7\)
17 to 26 is \(+9\)
You can see the difference increases by 2 each time. Therefore, the next number must be \(26 + 11 = 37\).

Key Point:

If you see a long sequence, assume it is a "Mixed Series"—meaning there are two sets of numbers hidden in one row. Try drawing lines between every other number to see the pattern!

2. Analogies

This involves finding the "relationship" between the first pair of words and applying that same relationship to the second pair. It's like matching meanings.

Common Relationships:

  • Component: e.g., Steering wheel : Car (The steering wheel is a part of the car)
  • Function/Use: e.g., Scissors : Cut (The function of scissors is to cut)
  • Location: e.g., Doctor : Hospital (A doctor works at a hospital)
  • Category/Type: e.g., Ant : Insect (An ant is a type of insect)

Pro Technique: "Create a Sentence"
Try making a short sentence with the first pair, then plug the second pair into the same sentence structure. If it sounds logical, that's the correct relationship!
Example: Bird : Fly and Fish : ?
Sentence: Birds use wings to fly.
Substitute: Fish use fins to swim (The answer is swim).

Did you know? Sometimes, multiple answers might look correct. Always choose the one that is the "closest" relationship and in the "same category/level" as the original pair.

3. Logical Reasoning

This part tests whether you can correctly draw conclusions from the given conditions. You must not use "personal feelings" or "external knowledge" to judge; look only at what the question provides.

Common Patterns:

1. "If... then...": If the cause happens, the effect must follow.
Example: If it rains, the road will be wet.
- If it is raining, we can conclude the road is wet (Correct).
- If the road is not wet, we can conclude it is not raining (Correct).

Common Pitfalls (Watch out!):

From the same example, if the question says "The road is wet," we "cannot conclude" that it is raining, because the road could be wet from a street cleaner!

2. "All/Some": Using Venn Diagrams will help a lot.
- All Thai people are kind (The circle of Thai people is inside the circle of kind people).
- Somchai is Thai (Somchai is a point inside the Thai circle).
- Conclusion: Somchai is kind.

Key Point: The words "some" or "some people" mean at least one person, but not necessarily everyone. Don't jump to conclusions that apply to the whole group!

4. Linguistic Logic (Conditions)

The question will provide long conditions, such as who sits where, who likes which color, or who is whose sibling. You need to organize that information.

Steps to Solve:

1. Create a Table: Highly recommended! Create a table or draw a diagram to keep things clear.
2. Fill in definite info first: Things stated clearly, such as "A sits next to B" or "C does not like red," should be noted down first.
3. Connect the dots: See which information shares common characters, and slowly connect the puzzle pieces.

Scenario Example:
Condition: A, B, and C are standing in a row, where A does not stand next to C.
Analysis: If A is not next to C, then B must be in the middle! The order must be A - B - C or C - B - A.

Key Takeaways

  • Numerical Series: Find the difference. If you don't find the pattern in the first layer, check the second layer.
  • Analogies: Use the "Create a Sentence" technique to verify relationships.
  • Logical Reasoning: Rely only on the given text. Don't overthink; Venn diagrams help!
  • Linguistic Logic: A "Table" is your best friend for organizing your thoughts.

For this part of the TGAT2 exam, "mindfulness" is most important. Questions often try to trick you into using personal feelings to make decisions. If you stick to the principles you've learned, a full score is well within your reach. Keep going—you've got this! ✌️