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From this section you can download / view Video Lectures on all subjects for all 6th, 7th, 8th, 9th and 10th classes/grades free of cost. The Videos for class 9th and 10th classes are prepared by SABAK Foundation for the ease of students as per new and updated syllabus/course prescribed by Federal Board of Intermediate & Secondary Education (FBISE), Islamabad – Pakistan and other BISE(s)/Boards of Pakistan and Directorate of Education, Islamabad – Pakistan. We are fully hopeful that after after watching/viewing these Video Lectures you will score 90% plus marks in your exams as they have been prepared in a very simple, easy, brief and in simple and lucid language to understand. For any queries you can contact us. We recommend you to like our Facebook Fan page for latest updates and new posts. You can also get our latest posts via Email directly in your Email Inbox by clicking here.

### Chapter 3: Variations (41 videos)

#### 3.1: Ratio, Proportion and Variations

- Concept of Ratio
- Problem 1: Concept of Ratio
- Direct Variations
- Problem 1: Direct Variations
- Problem 2: Direct Variations
- Inverse Variations
- Problem 1: Inverse Variations
- Problem 2: Inverse Variations
- Problem 3: Inverse Variations
- Introduction to Proportion
- Problem 1: Introduction to Proportion
- Law of Proportion
- Problem 1: Law of Proportion
- Fourth Proportional
- Problem 1: Fourth Proportional
- Third Proportional
- Problem 1: Third Proportional
- Mean Proportional
- Problem 1: Mean Proportional
- Continued Proportional
- Problem 1: Continued Proportional

#### 3.2: Theorems on Proportions

- Invertendo Theorem
- Problem 1: Invertendo Theorem
- Alternando Theorem
- Problem 1: Alternando Theorem
- Componendo Theorem
- Problem 1: Componendo Theorem
- Dividendo Theorem
- Problem 1: Dividendo Theorem
- Componendo-Dividendo Theorem
- Problem 1: Componendo-Dividendo Theorem
- Problem 2: Componendo-Dividendo Theorem

#### 3.3: Joint Variation

#### 3.4: K-Method

- Introduction to K-Method
- Problem 1: Introduction to K-Method
- Problem 2: Introduction to K-Method
- Problem 3: Introduction to K-Method
- Word Problem of Ratio of Shadow & Height
- Problem 1: Word Problem of Ratio of Shadow & Height