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Substitutional Coding

Introduction

Substitutional Coding is one of the most logic-driven patterns in coding-decoding questions. Here, instead of replacing letters with other letters or numbers, whole words are replaced by other words or phrases according to a given rule. The key challenge is to decode the substitution chain by carefully analyzing each replacement instruction.

Pattern: Substitutional Coding

Pattern

In this pattern, one word is replaced (substituted) with another as per a given statement or rule. The logic is found by tracing how one term is mapped to another, step by step.

Example rules might say: “If ‘blue’ means ‘red’, and ‘red’ means ‘green’, what is the color of the sky?” The key idea is to follow the chain of substitution until the true meaning is reached.

Step-by-Step Example

Question

If “black” means “white”, “white” means “green”, and “green” means “red”, then what is the color of milk?

Options:
A) Black
B) White
C) Green
D) Red

Solution

  1. Step 1: Identify the actual color of milk

    Normally, milk is white.

  2. Step 2: Apply the substitution chain

    The word “white” is replaced with “green” according to the question’s rule.

  3. Step 3: Determine the final code

    Therefore, in the given code, milk (which is white) will be represented as green.

  4. Final Answer:

    Green → Option C

  5. Quick Check:

    If “white” → “green”, then milk (normally white) → “green” ✅

Quick Variations

1. Multi-level substitution chains (e.g., A→B, B→C).

2. Meaning swap across categories (e.g., numbers for colors).

3. Reverse logic (decoding what the original term meant).

4. Conditional substitutions applied based on position or type of object.

Trick to Always Use

  • Step 1: Write down all substitution mappings clearly in a list or table.
  • Step 2: Start from the actual meaning and trace through each mapping carefully.
  • Step 3: Always follow the direction of substitution - not reverse unless clearly stated.
  • Step 4: Check the context (e.g., “color of sky” vs “word used for sky”).

Summary

Summary

  • Substitutional coding replaces full words or ideas with other words based on a mapping rule.
  • To decode, trace the chain of replacements step-by-step from the original term.
  • Always maintain clear direction - substitute exactly as defined.
  • Verify by reversing the chain if needed to ensure consistency.

Example to remember:
If “sun” means “moon”, “moon” means “star”, then the code for sun → “moon”, and for moon → “star”.

Practice

(1/5)
1. If “blue” means “green”, “green” means “red”, and “red” means “yellow”, then what is the color of grass?
easy
A. Blue
B. Green
C. Red
D. Yellow

Solution

  1. Step 1: Identify actual color

    Grass is normally green.

  2. Step 2: Apply substitutions

    ‘Green’ means ‘Red’.

  3. Step 3: Determine final code

    Hence, ‘Grass’ → ‘Red’.

  4. Final Answer:

    Red → Option C

  5. Quick Check:

    Green → Red → correct mapping ✅
Hint: Start from the actual property (color of object) before substitution.
Common Mistakes: Directly substituting without identifying the actual property first.
2. If “apple” means “banana”, “banana” means “grape”, and “grape” means “mango”, what is the code for 'banana'?
easy
A. Apple
B. Grape
C. Mango
D. Banana

Solution

  1. Step 1: Trace mapping

    ‘Apple’ → ‘Banana’, ‘Banana’ → ‘Grape’, ‘Grape’ → ‘Mango’.

  2. Step 2: Identify the chain

    The code for 'banana' is what 'banana' means, i.e., ‘grape’.

  3. Final Answer:

    Grape → Option B

  4. Quick Check:

    Banana maps directly to Grape ✅
Hint: Follow direct substitution arrows carefully - one level only.
Common Mistakes: Overextending the substitution chain beyond one step.
3. If “dog” means “cat”, “cat” means “rat”, and “rat” means “lion”, what is the code for 'dog'?
easy
A. Cat
B. Rat
C. Lion
D. Tiger

Solution

  1. Step 1: Follow rule

    ‘Dog’ → ‘Cat’, ‘Cat’ → ‘Rat’, ‘Rat’ → ‘Lion’.

  2. Step 2: Apply substitution once

    Code for ‘dog’ = ‘cat’.

  3. Final Answer:

    Cat → Option A

  4. Quick Check:

    Dog → Cat → single substitution correct ✅
Hint: Apply substitution exactly once unless the question says 'twice'.
Common Mistakes: Going too far down the substitution chain.
4. If 'pen' means 'pencil', 'pencil' means 'eraser', and 'eraser' means 'book', then what is 'book' coded as?
medium
A. Eraser
B. Pencil
C. Pen
D. Book

Solution

  1. Step 1: Decode rule

    Pen→Pencil, Pencil→Eraser, Eraser→Book.

  2. Step 2: Find mapping for 'book'

    No further substitution given for 'book'.

  3. Step 3: Conclude

    Hence, 'book' remains 'book'.

  4. Final Answer:

    Book → Option D

  5. Quick Check:

    ‘Book’ has no substitution mapping defined ✅
Hint: If no mapping exists, keep the original word unchanged.
Common Mistakes: Trying to apply reverse mapping unnecessarily.
5. If 'teacher' means 'student', 'student' means 'principal', and 'principal' means 'guide', who teaches in the school according to the code?
medium
A. Principal
B. Student
C. Guide
D. Teacher

Solution

  1. Step 1: Identify the role

    In real context, the one who teaches is the 'teacher'.

  2. Step 2: Apply mapping

    ‘Teacher’ means ‘Student’.

  3. Step 3: Derive coded answer

    Hence, in code language, the one who teaches is the student.

  4. Final Answer:

    Student → Option B

  5. Quick Check:

    ‘Teacher’ → ‘Student’; rule applied correctly ✅
Hint: Map logical meaning first, then replace using the given chain.
Common Mistakes: Confusing actual role with coded word.

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