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Cracking the Code: Mastering Investment Banking Interview Puzzles for Success

Why investment banks use puzzles in interviews

Investment banks use puzzles in interviews for several reasons. Firstly, puzzles help assess a candidate's problem-solving skills and critical thinking abilities. Investment banking roles often require quick thinking and the ability to analyze complex situations, so puzzles serve as a way to gauge a candidate's aptitude in these areas. Additionally, puzzles can test a candidate's creativity and ability to think outside the box, which are important traits in the investment banking industry. Finally, puzzles can also assess a candidate's ability to handle pressure and work well under time constraints, as they often have to solve these puzzles within a limited timeframe during interviews.

Another reason why investment banks use puzzles is to see how well a candidate can handle ambiguity. In the investment banking industry, situations can be complex and unclear, and puzzles simulate these types of scenarios. By presenting candidates with puzzles that may not have a clear solution, investment banks can evaluate their ability to handle uncertainty and come up with logical and well-reasoned solutions.

Overall, puzzles provide investment banks with a unique way to evaluate candidates beyond traditional interview questions and assess their suitability for the demanding and fast-paced nature of the industry.


Brain Teasers Puzzle
Brain Teasers Puzzle

Types of puzzles commonly asked in investment banking interviews

In investment banking interviews, candidates can expect to encounter a variety of puzzles. Some common types of puzzles include logic puzzles, math puzzles, and brainteasers. Logic puzzles often involve a series of clues or conditions that need to be logically deduced to arrive at the correct solution. These puzzles test a candidate's ability to think analytically and make logical deductions based on the given information.

Math puzzles, on the other hand, require candidates to apply mathematical concepts and principles to solve a problem. These puzzles can range from simple arithmetic calculations to more complex mathematical equations or patterns. Strong quantitative skills are essential for success in investment banking, so math puzzles help evaluate a candidate's numerical aptitude.

Brainteasers are another type of puzzle commonly asked in investment banking interviews. These puzzles often involve unconventional or creative problem-solving approaches and can cover a wide range of topics. Brainteasers assess a candidate's ability to think outside the box and come up with innovative solutions to challenging problems.


It's important for candidates to familiarize themselves with these different types of puzzles and practice solving them to improve their problem-solving skills and increase their chances of success in investment banking interviews.


Tips for solving investment banking interview puzzles

Solving investment banking interview puzzles can be challenging, but with the right approach, candidates can improve their chances of success. Here are some tips for solving these puzzles:

  • Read the puzzle carefully and make sure you understand the requirements and constraints before starting to solve it.

  • Break the problem down into smaller, more manageable parts. This can help simplify the puzzle and make it easier to solve.

  • Use logical reasoning and critical thinking skills to analyze the given information and make deductions or inferences.

  • Don't be afraid to think outside the box and consider unconventional approaches or solutions.

  • Practice solving different types of puzzles to improve your problem-solving skills and become more comfortable with the process.

  • Manage your time effectively during the interview. If you're stuck on a puzzle, it's better to move on and come back to it later if there's time remaining.

By following these tips, candidates can approach investment banking interview puzzles with confidence and increase their chances of solving them successfully.


Practice resources for investment banking interview puzzles

To prepare for investment banking interview puzzles, candidates can take advantage of various practice resources. Some recommended resources include:

  • Online puzzle-solving platforms and websites: These platforms provide a wide range of puzzles and brainteasers that are similar to the ones asked in investment banking interviews. Solving puzzles on these platforms can help candidates familiarize themselves with different types of puzzles and improve their problem-solving skills.

  • Books on puzzles and brainteasers: There are many books available that specifically focus on puzzles and brainteasers for interview preparation. These books often provide explanations and solutions for each puzzle, allowing candidates to learn from their mistakes and understand the underlying problem-solving techniques.

  • Mock interviews and case study practice: Participating in mock interviews or case study practice sessions can help candidates simulate the interview environment and experience solving puzzles under time pressure. This can improve their performance and confidence during the actual interview.

By utilizing these practice resources, candidates can enhance their puzzle-solving abilities and be better prepared for investment banking interviews.


10 Brain teasers Questions for Investment banking

In investment banking interviews, it is common to encounter brain teaser questions that test your analytical thinking skills. These questions are designed to assess your ability to solve complex problems under pressure. Here are 10 brain teaser questions frequently asked in investment banking interviews, along with detailed and logical answers:


1. The Two Rope Puzzle:

You have two ropes, each of which takes exactly 60 minutes to burn. However, the ropes do not burn at a consistent rate throughout their length. How can you measure exactly 45 minutes using only these two ropes?


Answer: To measure 45 minutes, follow these steps:

  • Light the first rope from both ends and the second rope from one end.

  • After 30 minutes, the first rope will burn out completely. At this point, light the second rope from the other end.

  • The second rope will now burn for an additional 15 minutes, resulting in a total of 45 minutes.


2. The Island and the Cannibals:

You are stranded on an island with three cannibals and three missionaries. Your goal is to transport all six individuals to the mainland using a boat that can only carry two people at a time. However, if the number of cannibals ever outweighs the number of missionaries on either the island or the boat, the cannibals will eat the missionaries. How can you safely transport everyone to the mainland?


Answer: To safely transport everyone to the mainland, follow these steps:

  • Take two cannibals to the mainland and leave them there.

  • Return to the island alone.

  • Take two missionaries to the mainland.

  • Leave one missionary on the mainland and take one cannibal back to the island.

  • Leave the cannibal on the island and take the remaining two cannibals to the mainland.

  • Return to the island alone.

  • Take two cannibals to the mainland.

  • Leave one cannibal on the mainland and take one missionary back to the island.

  • Leave the missionary on the island and take the remaining two missionaries to the mainland.

  • Return to the island alone.

  • Take two cannibals to the mainland.

  • Leave one cannibal on the mainland and take one missionary back to the island.

  • Leave the missionary on the island and take the remaining two cannibals to the mainland.

Now, all six individuals have been safely transported to the mainland without any cannibals eating the missionaries.


3. The Burning Rope Puzzle:

You have two ropes, each of which takes exactly 1 hour to burn. However, these ropes do not burn at a consistent rate throughout their length. How can you measure exactly 45 minutes using only these two ropes?


Answer: To measure 45 minutes, follow these steps:

  • Light the first rope from both ends and the second rope from one end.

  • After 30 minutes, the first rope will burn out completely. At this point, light the second rope from the other end.

  • The second rope will now burn for an additional 15 minutes, resulting in a total of 45 minutes.


4. The Three Light Bulbs Puzzle:

You are in a room with three light bulbs. Outside the room, there are three switches that correspond to the light bulbs inside. You cannot see the bulbs from the outside, and the switches are in the off position. You can manipulate the switches however you like, but once you open the door to the room, you cannot touch the switches anymore. How can you determine which switch corresponds to each light bulb?


Answer: To determine which switch corresponds to each light bulb, follow these steps:

  • Turn one switch on and leave it on for a few minutes.

  • Turn another switch on and then turn the first switch off.

  • Enter the room and observe the bulbs.

  • The bulb that is on corresponds to the switch that was turned on and off.

  • The bulb that is off and still warm corresponds to the switch that was turned on.

  • The bulb that is off and cool corresponds to the switch that was never turned on.


5. The Poisoned Wine Puzzle:

You have 1000 bottles of wine, and one of them is poisoned. The poison takes effect exactly 24 hours after ingestion. You have 10 rats to test which bottle is poisoned, but the poison is lethal even in small doses. How can you determine which bottle is poisoned within 24 hours?


Answer: To determine which bottle is poisoned within 24 hours, follow these steps:

  • Label the bottles from 1 to 1000.

  • Divide the bottles into 10 groups, with each group containing 100 bottles.

  • Mix a small portion of each bottle from a group together to create a mixture.

  • Feed each mixture to a different rat.

  • If a rat dies, the group of bottles from which the mixture was made contains the poisoned bottle.

  • If no rats die, the poisoned bottle is in the group of bottles that was not tested.

  • Divide the group of bottles that contains the poisoned bottle into 10 smaller groups, with each group containing 10 bottles.

  • Repeat the process with the rats, feeding them mixtures made from the smaller groups of bottles.

  • Eventually, you will narrow down the search to a single bottle that is poisoned.


6. The Chessboard Puzzle:

You have a standard 8x8 chessboard and 32 dominoes, each of which covers exactly two adjacent squares on the board. Is it possible to cover the entire chessboard with the dominoes, removing two squares from the board?

Answer: No, it is not possible to cover the entire chessboard with the dominoes while removing two squares from the board. Each domino covers exactly one white and one black square, and a standard chessboard has 32 white squares and 32 black squares. Therefore, it is impossible to cover the entire board with dominoes without removing at least one square of the same color.


7. The Two Eggs Puzzle:

You have two identical eggs and access to a 100-story building. The eggs have the same strength, but if an egg is dropped from a certain floor or higher, it will break. Your task is to determine the highest floor from which you can drop an egg without it breaking, using the fewest number of drops possible. How can you accomplish this?


Answer: To determine the highest floor from which you can drop an egg without it breaking using the fewest number of drops, follow these steps:

  • Start by dropping the first egg from the 50th floor.

  • If the egg breaks, you know the highest floor you can drop from without it breaking is between the 1st and 49th floors. Use the second egg to test each floor individually, starting from the 1st floor, until you find the highest floor from which the egg does not break.

  • If the first egg does not break when dropped from the 50th floor, you know the highest floor you can drop from without it breaking is between the 51st and 100th floors. Use the second egg to test each floor individually, starting from the 51st floor, until you find the highest floor from which the egg does not break.This method ensures that you find the highest floor with the fewest number of drops.


8. The Prisoners and the Light Bulb Puzzle:

There are 100 prisoners in solitary cells, each with a light bulb that is either on or off. The prisoners cannot communicate with each other, but they can see each other's cells. One day, the warden decides to play a game. He offers the prisoners a chance to go free if they can determine the status of their own light bulb. The prisoners are allowed to consult with their cellmates before making a guess, but if any prisoner guesses incorrectly, they will all remain in prison forever. How can the prisoners devise a strategy to ensure that at least one of them guesses correctly and they all go free?


Answer: The prisoners can devise a strategy as follows:

  • Designate one prisoner as the counter.

  • The counter will keep track of the number of times they see a light bulb on.

  • Each prisoner will assume that their light bulb is off and act accordingly.

  • If a prisoner sees an odd number of light bulbs on, they will turn their own light bulb on. Otherwise, they will keep it off.

  • After a certain number of days, the counter will know if their light bulb is on or off based on the total count of light bulbs they have seen on.

  • On the final day, when the warden asks for their answer, the counter will guess based on the status of their own light bulb.

  • At least one prisoner will guess correctly and they will all go free.


9. The Bridge and the Flashlight Puzzle:

You and three friends are trapped on one side of a bridge that will collapse in 17 minutes. The bridge is too dark to cross without a flashlight, and you only have one flashlight. Each person takes a different amount of time to cross the bridge: 1 minute, 2 minutes, 5 minutes, and 10 minutes. When two people cross the bridge together, they must move at the slower person's pace. How can you all cross the bridge in 17 minutes or less?


Answer: To cross the bridge in 17 minutes or less, follow these steps:

  • The two fastest people (1 minute and 2 minutes) cross the bridge together, taking 2 minutes.

  • The fastest person (1 minute) takes the flashlight and goes back to the starting point, taking 1 minute.

  • The two slowest people (5 minutes and 10 minutes) cross the bridge together, taking 10 minutes.

  • The second fastest person (2 minutes) takes the flashlight and goes back to the starting point, taking 2 minutes.

  • Finally, the two fastest people (1 minute and 2 minutes) cross the bridge together one last time, taking 2 minutes.

In total, it takes 2 + 1 + 10 + 2 + 2 = 17 minutes for all four people to cross the bridge.


10. The Weighing Coins Puzzle:

You have 12 identical coins, but one of them is either heavier or lighter than the others. You have a balance scale that can only be used three times. How can you determine which coin is different and whether it is heavier or lighter?


Answer: To determine which coin is different and whether it is heavier or lighter, follow these steps:

  • Divide the 12 coins into three groups of four.

  • Weigh two of the groups against each other on the balance scale.

  • If the two groups weigh the same, the different coin is in the third group of coins. Proceed to step 4.

  • If one of the groups is heavier, the different coin is in that group. Proceed to step 3.

  • Take the group of four coins that is different and weigh two of the coins against each other on the balance scale.

  • If one of the coins is heavier, that coin is the different one and it is heavier. Proceed to step 5.

  • If the two coins weigh the same, the different coin is one of the remaining two coins in the group. Proceed to step 6.

  • Take the remaining two coins and weigh them against each other on the balance scale.

  • The coin that is heavier is the different one and it is heavier.

  • If the two coins weigh the same, the different coin is the one that was not weighed.

By following these steps, you can determine which coin is different and whether it is heavier or lighter using the balance scale three times.


These are just a few examples of the analytical puzzles you may encounter in investment banking interviews. Remember to approach these questions with a logical and systematic mindset, breaking down the problem into smaller steps and considering all possibilities. Practice solving these puzzles to sharpen your analytical thinking skills and increase your chances of success in your next investment banking interview.






Common mistakes to avoid when solving investment banking interview puzzles

When solving investment banking interview puzzles, it's important to avoid certain common mistakes that can hinder success. Here are some mistakes to avoid:

  • Jumping to conclusions without fully understanding the puzzle: It's crucial to read and analyze the puzzle carefully before attempting to solve it. Jumping to conclusions too quickly can lead to incorrect answers.

  • Ignoring important information: Puzzles often contain crucial information that can help guide the solution. Ignoring or overlooking this information can result in incorrect or incomplete solutions.

  • Overcomplicating the problem: Sometimes, the simplest solution is the correct one. Overcomplicating the problem by introducing unnecessary complexity can make it harder to find the right answer.

  • Not managing time effectively: Time management is key during investment banking interviews. Spending too much time on a single puzzle can leave less time for other questions, potentially impacting overall performance.

  • Relying solely on memorization: Memorizing solutions to specific puzzles may not be effective as interviewers often modify or present similar puzzles with different variations. It's important to focus on building problem-solving skills rather than relying on memorization.

By avoiding these common mistakes, candidates can improve their puzzle-solving approach and increase their chances of success in investment banking interviews.


Case studies of successful puzzle-solving strategies

To further understand effective puzzle-solving strategies in investment banking interviews, let's explore a few case studies of successful candidates:


Case Study 1: John, a candidate for an investment banking analyst position, approached each puzzle systematically. He carefully read and analyzed the given information, made logical deductions, and broke down complex problems into simpler parts. John also managed his time effectively, ensuring he didn't spend too much time on a single puzzle. His structured approach and critical thinking skills impressed the interviewers, leading to a job offer.


Case Study 2: Sarah, another candidate, focused on thinking outside the box and considering unconventional approaches to solve puzzles. She demonstrated creativity and innovative problem-solving skills, which set her apart from other candidates. Sarah's ability to come up with unique solutions to challenging problems impressed the interviewers and secured her a spot in the final round of interviews.

These case studies highlight the importance of both systematic thinking and creative problem-solving in investment banking interview puzzles. By adopting a balanced approach and leveraging their strengths, candidates can stand out and increase their chances of success.


How to prepare for investment banking interviews beyond puzzles

While investment banking interview puzzles are an important component, it's crucial for candidates to prepare for other aspects of the interview as well. Here are some tips for comprehensive interview preparation:


  • Research the company: Familiarize yourself with the investment bank you're interviewing with. Understand their services, recent deals, company culture, and values. This knowledge can help you tailor your answers and demonstrate your interest in the firm.

  • Brush up on technical knowledge: Investment banking interviews often include technical questions related to finance, accounting, valuation, and financial modeling. Reviewing these concepts and practicing relevant calculations can help you feel more confident during the interview.

  • Develop your story: Prepare concise and compelling responses to common interview questions such as 'Tell me about yourself' and 'Why do you want to work in investment banking?' Highlight your relevant experiences, skills, and motivations to make a strong impression.

  • Practice behavioral and situational questions: Investment banking interviews also include behavioral and situational questions to assess your fit with the firm and your ability to handle different scenarios. Practice answering these types of questions to articulate your experiences and demonstrate your problem-solving and leadership skills.

  • Mock interviews: Consider conducting mock interviews with peers, mentors, or professionals in the industry. Mock interviews can help you practice answering questions, receive feedback, and improve your interview performance.

By preparing comprehensively beyond just puzzles, candidates can showcase their knowledge, skills, and suitability for investment banking roles.


Investment banking interview puzzle success stories

Here are a few success stories of candidates who excelled in investment banking interview puzzles:


Success Story 1: Mark, a recent graduate, spent several weeks practicing different types of puzzles and brainteasers. He analyzed the patterns and strategies behind each puzzle and built a strong foundation in problem-solving skills. During his interview, Mark confidently approached the puzzles, applying the techniques he had learned. His ability to think critically, make logical deductions, and communicate his thought process impressed the interviewers, leading to a job offer.


Success Story 2: Emily, an experienced professional transitioning into investment banking, focused on honing her quantitative skills and mathematical abilities. She dedicated time to solving math puzzles and practicing mental calculations. Emily's numerical aptitude and ability to solve complex mathematical problems efficiently set her apart from other candidates. Her strong performance in the puzzles showcased her quantitative capabilities and secured her a position in the final round of interviews.


These success stories demonstrate the value of dedicated practice and preparation in investment banking interview puzzles. By investing time and effort in improving problem-solving skills, candidates can increase their chances of success and stand out from the competition.


Conclusion: The importance of mastering investment banking interview puzzles

Mastering investment banking interview puzzles is crucial for success in the competitive world of investment banking. Puzzles serve as a unique way for investment banks to assess a candidate's problem-solving skills, critical thinking abilities, creativity, and ability to handle ambiguity. By understanding why investment banks use puzzles, familiarizing themselves with the types of puzzles commonly asked, and following effective puzzle-solving strategies, candidates can increase their chances of acing these interviews.


However, it's important to remember that investment banking interviews encompass more than just puzzles. Comprehensive preparation that includes researching the company, brushing up on technical knowledge, developing a compelling story, practicing behavioral and situational questions, and conducting mock interviews is essential for success.

By combining puzzle-solving skills with a well-rounded preparation approach, candidates can position themselves as strong contenders and increase their chances of securing coveted investment banking roles.



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