Basics of Counting in Engineering Mathematics

Syllabus Overview:

  • Probability and Statistics: Covers probability theory, random variables, distributions, and data interpretation.

  • Calculus: Focuses on differentiation, integration, limits, continuity, and partial derivatives.

  • Linear Algebra: Involves matrices, determinants, vector spaces, eigenvalues, and eigenvectors.

Understanding the Basics of Counting is crucial before diving into probability and combinatorics.

Counting Principles

When dealing with selections or arrangements, we use two fundamental principles: Addition and Multiplication.

1. Fundamental Principle of Addition

Formal Definition:

If a task can be done in ‘m’ ways and another task can be done in ‘n’ ways, and only one task is to be performed, the total number of ways is:

                                                                              m+n

Simple Language:

When you feel the following keywords occur in the question:

  • either one task,

  • or another task,

  • only one option, then apply the Addition Principle.


2. Fundamental Principle of Multiplication

Formal Definition:

If a task can be done in ‘m’ ways and after that another task can be done in ‘n’ ways, then the total number of ways to perform both tasks is:

                                                                             m×n

Simple Language:

When you feel the following keywords occur in the question:

  • and,

  • both,

  • all tasks together, then apply the Multiplication Principle.


Solved Examples

Let’s practice with some simple real-world examples:


Example 1: (Multiplication Principle)

Question:
There are 5 boys and 7 girls in a class. In how many ways can we select a boy and a girl?

Solution:
Since the task involves both boy and girl, we multiply:

5×7=35 ways


Example 2: (Addition Principle)

Question:
There are 5 boys and 7 girls in a class. In how many ways can we select a boy or a girl?

Solution:
Since it’s a choice between a boy or a girl, we add:

5+7=12 ways


Example 3: (Multiplication Principle)

Question:
You have 3 shirts and 4 trousers. How many ways can you dress by selecting one shirt and one trouser?

Solution:
Feeling of both shirt and trouser → Multiplication:

3×4=12 ways


Example 4: (Addition Principle)

Question:
A student can choose either Mathematics (5 options) or Physics (4 options) as an elective. How many ways can the choice be made?

Solution:
Feeling of either one subject → Addition:

5+4=9 ways

Conclusion

In this introductory blog on Engineering Mathematics, we:

  • Explored the syllabus structure.

  • Understood the Fundamental Principle of Addition and Multiplication.

  • Solved simple examples for clarity.

Mastering these basic counting concepts is crucial before moving ahead to permutations, combinations, and advanced probability.

Stay tuned for the next topic: Permutations and Combinations Simplified!

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