Average - Short Tricks to Find Average Speed

Duration: 7 min

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Module outline

  1. Mathematics: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Powers and Exponents (Surds and Indices), Algebra, Probability, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Mental Ability, Age Problems, Partnership, Statistics, Arithmetic, Speed Mathematics and Basic Mathematics
  2. General Intelligence & Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Crypt Arithmetic, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, Clerical Aptitude, Verbal Classification
  3. General Awareness: Polity, Evolution of Indian Banking (Banking & Financial Awareness), Physics, Biology, Chemistry, History, Geography, Indian Economy, Static General Knowledge, GK- Current Affairs, NEP 2020, Environment
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video is a tutorial on calculating average speed for different scenarios, presented by an instructor in a split-screen format. The video begins with a title card and then introduces a problem where a 'Corona Virus' travels from Mumbai to Delhi at 40 km/hr and returns at 60 km/hr, asking for the average speed. The instructor, Yash Jain, explains the fundamental formula for average speed: total distance divided by total time. He demonstrates the solution by assuming a distance 'x' for the one-way trip, calculating the time for each leg (x/40 and x/60), summing them to get total time, and then dividing the total distance (2x) by the total time to find the average speed, which is 48 km/hr. The video then transitions to a second problem involving multiple segments with different distances and speeds, and finally, it presents a general formula for average speed when the distance for each segment is equal, which is 2*S1*S2/(S1+S2). The video concludes with a summary of the key formulas and a 'Thanks for Watching' screen.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title card displaying the word 'AVERAGE' in a futuristic, glowing font against a dark, digital background. It then transitions to a split-screen view of a lecture. The main screen is a blackboard with a question written in yellow: 'Q1: Corona Virus goes from Mumbai to Delhi at the speed of 40 km/hr and returns back to Mumbai at 60 km/hr. Find the average speed in km/hr?'. The options are (a) 50, (b) 48, (c) 52, (d) Data Insufficient. A small yellow sticky note with the word 'Important' is visible. The instructor, Yash Jain, appears in a small window at the bottom right, introducing the topic. He states that a trick to solve this question in 20 seconds will be discussed at the end of the video.

  2. 2:00 – 5:00 02:00-05:00

    The instructor begins solving the first problem on the blackboard. He writes the fundamental formula for average speed: 'Avg Speed = Total distance / Total time'. He then sets up the problem by letting the distance from Mumbai to Delhi be 'x'. He writes the time for the first leg as 'x/40' and for the return leg as 'x/60'. He calculates the total time as 'x/40 + x/60' and the total distance as '2x'. He then substitutes these into the average speed formula, resulting in '2x / (x/40 + x/60)'. He simplifies this expression by factoring out 'x' from the denominator, leading to '2 / (1/40 + 1/60)'. He then calculates the sum in the denominator as '100/2400' or '1/24', and finally, the average speed as '2 / (1/24) = 48 km/hr'. He confirms that the correct answer is (b) 48.

  3. 5:00 – 7:00 05:00-07:00

    The video transitions to a second problem, Q2, which involves multiple segments: 10 km at 5 km/hr, 30 km at 6 km/hr, and 20 km at 10 km/hr. The instructor explains that this is a case where distances are not equal. He then introduces a general formula for average speed when the distance for each segment is equal, which is '2*S1*S2 / (S1+S2)'. He writes this formula on the board and then shows how it applies to the first problem, with S1=40 and S2=60, resulting in '2*40*60 / (40+60) = 4800/100 = 48 km/hr'. He then briefly mentions that for more than two segments with equal distance, the formula is '3*S1*S2*S3 / (S1*S2 + S2*S3 + S1*S3)'. The video ends with a 'Thanks for Watching' screen.

The video provides a clear, step-by-step tutorial on calculating average speed, starting with a specific problem and then generalizing the solution. It effectively teaches the core concept that average speed is total distance over total time, and then demonstrates how to apply this to a round trip with different speeds. The instructor uses a consistent method of setting up variables and simplifying equations, which is a valuable problem-solving technique. The video also introduces a key shortcut formula for equal-distance trips, making it a comprehensive resource for students preparing for competitive exams.

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