TLDR;
This video provides a detailed walkthrough of a math question paper for the IB Security Assistant exam. The instructor solves 15 questions from a previous year's paper, offering explanations and shortcuts. The session also includes information about a free test for IB Security aspirants and encourages viewers to share the opportunity with their peers. The instructor categorizes the questions by difficulty level to provide insights into exam patterns and preparation strategies.
- Solving previous year questions for IB Security Assistant exam.
- Providing shortcuts and tricks to solve questions quickly.
- Encouraging students to attempt free test for IB Security.
Introduction [1:18]
The instructor greets the students and outlines the plan to solve previous year questions for the IB Security Assistant exam, also providing practice questions. He mentions that students who are preparing for IB Security Assistant exam should work hard for the remaining 10 days. He announces that there will be three classes daily, including one on YouTube, to cover more material.
Free Test Announcement [2:11]
The instructor informs students about a free IB Security test available from September 21st to 22nd, with results declared on September 22nd at 3:00 pm. He emphasizes that the test is exam-oriented and will provide rankings to assess performance. He encourages everyone to register and inform their friends about the test, regardless of their connection to the KGS platform.
Question 1: Average of Square Numbers [3:13]
The first question involves finding the average of square numbers between 20 and 70. The square numbers are 25, 36, 49, and 64. Adding these gives 174, which when divided by 4 (the number of values) results in an average of 43.5. Thus, option A is the correct answer.
Question 2: Percentage Difference [4:41]
The second question states that the difference between two numbers is 1140, where 6% of the first number equals 10% of the second number. By setting up the equation 6% of x = 10% of y, the ratio of x to y is found to be 5:3. Given the difference of 1140 corresponds to 2 units, one unit equals 570. The greatest number, represented by 5 units, is therefore 2850, making option D the answer.
Question 3: Mixture and Alligation [6:51]
The third question involves a mixture of milk and water in a 90-liter solution with a ratio of 4:5. The ratio is reversed to 5:4 after adding milk. To equalize the quantity of water, the LCM of 5 and 4, which is 20, is used. The initial mixture is 36 units, and the increase in milk is 9 units. The value of 9 units is found to be 22.5 liters, making option C the correct answer.
Question 4: LCM of Prime Numbers [9:53]
The fourth question states that the LCM of two prime numbers is 667. The instructor explains that the LCM of two prime numbers is their product. By hit and trial, 667 is found to be the product of 23 and 29. Given that the larger number is x and the smaller is y, the expression 5y - 3x is calculated as 5 * 23 - 3 * 29 = 115 - 87 = 28. Option D is the correct answer.
Question 5: Percentage Calculation [12:06]
The fifth question involves finding 41% of a number, given that 15% of the number multiplied by 55% equals 2475. The instructor sets up the equation and simplifies it to find that 41% of the number is 12300, making option B the correct answer. A shortcut is also mentioned: directly look for a multiple of 41 in the options.
Question 6: Profit and Loss [15:14]
The sixth question involves profit and loss calculations. The cost price of 15 items equals the selling price of 10 items, giving a purchase price to selling price ratio of 2:3, which means a profit percentage of 50%. The discount on 12 apples equals the profit on 4 apples, giving a discount to profit ratio of 1:3. By equating the profit values and finding the marked price, the discount percentage is calculated as 10%. The difference between the profit percentage (50%) and the discount percentage (10%) is 40%, making option D the correct answer.
Question 7: Volume of Bricks [21:01]
The seventh question involves calculating the number of additional bricks needed to complete a wall. The wall's dimensions are 50m x 30m x 40m, giving a total volume of 60,000 cubic meters. The dimensions of one brick are 3m x 2m x 1m, and 6500 bricks have already been used, occupying a volume of 39,000 cubic meters. The remaining volume is 21,000 cubic meters, requiring 3500 more bricks, making option D the correct answer.
Question 8: Time and Work - Alternate Days [25:50]
Question eight involves time and work, where A and B can complete a task in 15 and 20 days respectively. Working alternatively, A starts and they work for 8 days. The LCM of 15 and 20 is 60, with A's efficiency being 4 and B's being 3. In 2 days, 7 units of work are completed. Over 8 days, 28 units are completed, leaving 32 units. The fraction of work remaining is 8/15, making option C the answer.
Question 9: Time and Work - Individual Contribution [28:31]
Question nine involves A and B completing a work in 20 and 30 days respectively. They work together for 5 days, and C completes the remaining work in 7 days. The LCM of 20 and 30 is 60, with A's efficiency being 3 and B's being 2. A works for 5 days, completing 15 units, and B works for 5 days, completing 10 units. C completes 35 units. The ratio of their work is 3:2:7, so option B is the answer.
Question 10: Time and Work - Alternate Support [31:07]
Question ten involves Jai, Naresh, and Sunil completing a work in 20, 30, and 60 days respectively. Jai works alone on the first day, and Naresh and Sunil support him on alternate days. The LCM of 20, 30, and 60 is 60, with efficiencies of 3, 2, and 1 respectively. In 2 days, 9 units of work are completed. In 12 days, 54 units are completed. Jai works alone on the 13th day, completing 3 units, leaving 3 units. Naresh and Sunil then complete the remaining work, resulting in a total of 13 1/2 days, so option C is the answer.
Question 11: Algebraic Expression [34:22]
Question eleven involves simplifying an algebraic expression given that x + 1/x = 6. The expression is simplified by dividing by x and substituting the value of x + 1/x. The value of y is also simplified. The ratio of the simplified expressions is found to be 12:7.
Question 12: Ratio and Proportion [37:55]
Question twelve involves ratio and proportion. The ratio of two numbers is 5:4. After subtracting y from each, the ratio becomes 2:1. The value of y is found to be 3. Adding y to the initial numbers results in a ratio of 8:7, so option D is the answer.
Question 13: Simple Interest [39:39]
Question thirteen involves simple interest. The simple interest on ₹6000 for 4 years at 8% is equal to the simple interest on ₹9000 for 2 years at R%. By equating the simple interest formulas, the value of R is found to be 9%.
Question 14: Triplet Values [41:07]
Question fourteen involves triplet values. Given 9^x + 40^x = 41^x, it's recognized that 9, 40, and 41 are triplet values, meaning they satisfy the Pythagorean theorem. Therefore, x = 2. The question asks for the value of x^2, which is 16.
Question 15: Trains and Distance [43:39]
Question fifteen involves two trains traveling at 10 km/h and 27 km/h. One train travels 340 km faster than the other. The ratio of their speeds is the same as the ratio of their distances. The difference in distance is 17 units, which equals 340 km. One unit equals 20 km. The total distance between A and B is 37 units, which equals 740 km, so option A is the answer.
Analysis and Homework [46:12]
The instructor provides an analysis of the questions, categorizing them by difficulty level. He assigns the 16th and 17th questions as homework and plans to solve the remaining questions in the next session. He encourages students to study well and promises to provide maximum guidance in the remaining 10 days.