Cost Price = Profit Percent

Duration: 10 min

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AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video presents a series of aptitude problems related to profit and loss, focusing on a specific type of question where the cost price (CP) is equal to the profit percentage (P%). The instructor, Yash Jain, begins by introducing the first problem involving Anushka Sharma selling a Parle-G biscuit for Rs. 56. He explains the conventional method, setting up the equation SP = CP(100 + P)/100 and substituting CP = P, leading to the quadratic equation x² + 100x - 5600 = 0, which he solves to find the cost price is Rs. 40. He then introduces a 'Hosh Udaane Wali Short Trick' as a faster method, using the formula CP * P% = SP, which simplifies to x * x = 56, or x² = 56. The video then proceeds to solve three more similar problems: Q2 with a selling price of Rs. 75, Q3 with a selling price of Rs. 21 where the cost price equals the loss percentage, and Q4 with a selling price of Rs. 25. For each problem, the instructor demonstrates both the conventional method and the short trick, emphasizing the efficiency of the latter. The video concludes with a 'Thanks for Watching' screen.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title card for a problem from the Deloitte 2018 exam. The problem states: 'Anushka Sharma sells a packet of Parle-G Biscuit. On selling that packet at Rs. 56, cost price becomes equal to the profit %. What is the cost price of that packet?'. The instructor, Yash Jain, introduces the 'Conventional Method' for solving this. He defines the variables: SP = Rs. 56, CP = P%, and sets CP = x. He writes the standard profit formula: SP = CP(100 + P)/100. Substituting the variables, he gets 56 = x(100 + x)/100.

  2. 2:00 – 5:00 02:00-05:00

    The instructor continues the conventional method. He multiplies both sides of the equation 56 = x(100 + x)/100 by 100 to get 5600 = 100x + x². He rearranges this into a standard quadratic equation: x² + 100x - 5600 = 0. He then solves this quadratic equation by factoring, finding the factors of 5600 that differ by 100, which are 140 and 40. This gives the equation (x + 140)(x - 40) = 0, leading to the solutions x = -140 or x = 40. Since cost price cannot be negative, he concludes the cost price is Rs. 40. He then introduces a 'Hosh Udaane Wali Short Trick' for this type of problem.

  3. 5:00 – 10:00 05:00-10:00

    The instructor explains the 'Hosh Udaane Wali Short Trick'. He states that when CP = P%, the product of CP and P% equals the selling price (SP). He writes the formula: CP * P% = SP, which becomes x * x = 56, or x² = 56. He then applies this trick to the first problem, showing that x = √56, which is approximately 7.48, but this contradicts the earlier correct answer of 40. He then moves to the next problem, Q2, which asks for the cost price when SP is Rs. 75 and CP = P%. He applies the short trick: x * x = 75, so x = √75 ≈ 8.66. He then applies the conventional method to Q3, where SP is Rs. 21 and CP = L%, leading to the equation x² - 100x - 2100 = 0. He solves this to find CP = 140. For Q4, with SP = Rs. 25 and CP = L%, he uses the short trick: x * x = 25, so x = 5. He then applies the conventional method to confirm this.

  4. 10:00 – 10:26 10:00-10:26

    The video concludes with a final screen displaying the text 'THANKS FOR WATCHING' in large white letters against a blue, abstract, digital background. This screen serves as the end card for the video, signaling the completion of the lesson.

The video systematically teaches a problem-solving strategy for a specific class of profit and loss questions where the cost price is numerically equal to the profit or loss percentage. It begins by establishing the conventional algebraic method, which involves setting up and solving a quadratic equation. The instructor then introduces a 'short trick' that leverages the relationship CP * P% = SP, which is a direct consequence of the given condition. The video demonstrates the application of both methods to four different problems, highlighting the efficiency of the short trick. The core learning objective is to equip students with a faster, more intuitive way to solve these types of problems, which are common in competitive exams like those for Deloitte, TCS, and CSE.

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