Important Practice Questions & Short Tricks
Duration: 6 min
This video lesson is available to enrolled students.
AI Summary
An AI-generated summary of this video lecture.
The video is a lecture on solving logical reasoning problems related to calendars, presented by an instructor from Knowledge Gate. The first problem, asked in a TCS interview, is a riddle about age: 'The day before yesterday, I was 25 years old, and next year I will turn 28.' The instructor explains that this is possible if the person's birthday is on December 31st and the current date is January 1st of a new year. On December 30th of the previous year, the person was 25. On December 31st, they turned 26. On January 1st of the current year, they are still 26, but they will turn 27 in the current year and 28 in the following year. The second problem asks for the maximum gap between two successive leap years, which is 8 years, as demonstrated by the sequence 1896, 1904, 1908, 1912, 1920, etc. The final problem asks how many weekends are in a year, with the instructor calculating that a year has 52 weeks and 1 or 2 extra days, leading to 52 or 53 weekends, with 53 being the maximum possible. The video uses a digital blackboard for calculations and includes on-screen text for the questions and options.
Chapters
0:00 – 2:00 00:00-02:00
The video opens with a title card for a 'CALENDAR' topic, followed by a lecture screen. The instructor, Yash Jain, introduces a logical puzzle: 'The day before yesterday, I was 25 years old, and next year I will turn 28. How is it possible?' The question is displayed on a green bar at the top. The instructor begins to analyze the problem, setting up the context of a TCS interview question from 2019. The background is a black digital board with white chalk-style drawings of school supplies. The instructor is visible in a small window in the bottom right corner.
2:00 – 5:00 02:00-05:00
The instructor begins to solve the age riddle on the digital blackboard. He writes 'DOB: 31st December' and then uses a timeline to explain the logic. He writes '31st December 2007 -> 25' and '30th December 2008 -> 26', showing that the person was 25 on December 30, 2007. He then writes '1st Jan 2008 -> 26' and '31st Dec 2009 -> 28', explaining that on January 1, 2008, the person is 26, and they will turn 27 in 2008 and 28 in 2009. The key insight is that the 'day before yesterday' was December 30, 2007, and 'next year' refers to 2009, when they will turn 28. The instructor uses arrows and dates to clearly illustrate the timeline.
5:00 – 6:27 05:00-06:27
The video transitions to a new problem: 'The maximum gap between two successive leap year is?'. The options are a) 4, b) 8, c) 2, d) 1. The instructor explains that a leap year occurs every 4 years, but century years are not leap years unless divisible by 400. He provides the example of 1896 and 1904, showing a gap of 8 years. He then moves to the next problem: 'How many weekends are there in a year?'. He explains that a year has 365 days, which is 52 weeks and 1 day, or 52 weeks and 2 days in a leap year. Since a weekend consists of 2 days (Saturday and Sunday), there are at least 52 weekends. In a non-leap year, the extra day could be a Saturday or Sunday, making it 53 weekends. In a leap year, the two extra days could be a Saturday and Sunday, also making it 53 weekends. The maximum is 53. The video ends with a 'THANKS FOR WATCHING' screen.
The video presents a structured lesson on calendar-based logical reasoning, progressing from a complex riddle to two more direct calculation problems. The core teaching method involves breaking down each problem into a clear, step-by-step logical process, often using a timeline or a digital blackboard to visualize the sequence of events. The first problem highlights the importance of carefully interpreting the temporal context of a statement, particularly the ambiguity of 'next year'. The second problem demonstrates the application of the rules for leap years, showing that the maximum gap is 8 years due to the century rule. The final problem applies basic division and understanding of the week cycle to determine the maximum number of weekends in a year. The synthesis of these problems is the application of logical deduction and fundamental calendar rules to solve seemingly paradoxical or quantitative questions.