TCS Previous Year Question on Alligation Rule

Duration: 11 min

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AI Summary

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This educational video, presented by Yash Jain, is a comprehensive tutorial on solving mixture and alligation problems, a common topic in competitive exams like the TCS exam. The lecture begins with an introduction to the core concept of alligation, which is a method to find the ratio in which two or more ingredients at different prices must be mixed to achieve a desired average price. The instructor first explains the 'Basic Rule of Alligation' using a diagram that visually represents the relationship between the lower price, higher price, and the average price, leading to the formula: (Higher Price - Average Price) : (Average Price - Lower Price). To demonstrate this, a practical example is solved using the traditional algebraic approach, where the prices of Item A (Rs. 450 per kg) and Item B (Rs. 510 per kg) are used to find the ratio for a mixture costing Rs. 475 per kg. The video then introduces a faster, more efficient method known as the 'X short trick,' which simplifies the calculation by directly subtracting the prices from the average price to get the ratio. The video concludes with a final 'Thanks for Watching' screen.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with an animated title card featuring a cartoon scientist in a lab, with the word 'MIXTURE' visible at the bottom. This transitions to a presentation slide with a geometric background, displaying the title 'MIXTURES & ALLIGATIONS' and the instructor's name, 'By Yash Jain'. A small video feed of the instructor, Yash Jain, is in the bottom right corner. He introduces the topic, explaining that the video will cover mixture and alligation problems, which are frequently asked in competitive exams such as the TCS exam.

  2. 2:00 – 5:00 02:00-05:00

    The instructor begins explaining the 'Alligation Rule'. The screen shows a handwritten note titled 'Basic Rule of Alligation'. The text explains that if item 'A' is sold at a lower price (x) and item 'B' at a higher price (y), and they are mixed in a ratio to get an average price (a), the required ratio is (y-a) : (a-x). A diagram is drawn with 'lower price (x)', 'higher price (y)', and 'average price (a)' connected by lines, visually representing the rule. The instructor then introduces a problem: 'Item A is sold at Rs. 450 per kg & Item B is sold at Rs. 510 per kg. In what ratio A & B should be mixed so that the mixture costs Rs. 475 per kg?'. He labels this as a 'Traditional Approach' and begins to solve it by setting up variables p and q for the quantities of A and B, respectively.

  3. 5:00 – 10:00 05:00-10:00

    The instructor continues the traditional approach. He writes the total cost as '450p + 510q' and the total quantity as 'p + q'. He then sets up the equation for the average price: (450p + 510q) / (p + q) = 475. He proceeds to solve this equation algebraically, multiplying both sides by (p + q) to get 450p + 510q = 475p + 475q. By rearranging terms, he finds 35q = 25p, which simplifies to the ratio p:q = 35:25, or 7:5. He then transitions to a faster method, the 'X short trick', by drawing a diagram with the prices 450, 510, and the average 475. He shows the differences: 510 - 475 = 35 and 475 - 450 = 25, and states that the ratio is 35:25, which simplifies to 7:5, matching the traditional method.

  4. 10:00 – 11:05 10:00-11:05

    The video concludes with a final screen. The background is a dark purple gradient. In the center, the text 'THANKS FOR WATCHING' is displayed in large, white, capitalized letters. This is the end of the lecture, summarizing the key takeaway that the 'X short trick' provides a quick and efficient way to solve alligation problems, which is particularly useful for time-constrained competitive exams.

The video provides a clear, step-by-step tutorial on solving mixture and alligation problems. It effectively contrasts the traditional, algebraic method with a faster, more intuitive 'X short trick'. The core concept, the alligation rule, is introduced with a visual diagram and a clear formula. The example problem is solved using both methods, demonstrating that they yield the same result (a 7:5 ratio) but that the shortcut is significantly quicker. The progression from theory to practical application, and from a slower method to a faster one, makes the content highly effective for students preparing for competitive exams.