Logical Reasoning/Puzzles Logical Reasoning Questions and Puzzles form an important part of an interview process. These are aimed towards checking aptitude and logical problem solving skills of an interviewee. In most of the cases, interviewers usually don’t worry too much about the final answer, but what is really looked at is the approach you take to solve a problem. Hence, it’s important to explain your approach and thought process to an interviewer. In this section, we have tried to list down and cover different types of puzzles through limited number of questions that can give you a good background and flair of puzzles asked. To highlight the approach taken to solve these puzzles, we have provided detailed explanations in the answers. 10 of them are placed heads up and 90 are placed tails up. You can’t feel, see or in any other way find out which side is up. Now, split the coins into two piles such that there are equal numbers of heads up in each pile. Make two piles of the coins. Put 10 coins in one pile and 90 coins in another. Now, both the piles have equal number of heads up. You are given eight identical looking balls. You are provided with a simple mechanical balance to weigh the ball. Two trials will be needed. Divide the balls in three groups. Both sides are equal. Both sides are not equal. Again, if both the sides are equal, you know that 3rd ball in the same group is heavier. Else, you would be able to see heavier ball from the balance. Prisoner W is standing on one side of a wall, and prisoners X Y and Z are standing on the other side of the wall. W || X Y Z Where, the || represents a wall. The wall has no mirrors. So, prisoner W can see the wall and nothing else. There are 2 white hats and 2 black hats and each prisoner has a hat on his head. Each prisoner cannot see the color of his own hat, and cannot remove the hat from his own head. But the prisoners do know that there are 2 white hats and 2 black hats amongst themselves. The prison guard says that if one of the prisoners can correctly guess the color of his hat then the prisoners will be set free and released. Note that the prisoners are not allowed to signal to each other, nor speak to each other to give each other hints. But, they can all hear each other if one of them tries to answer the question. Also, you can assume that every prisoner thinks logically and knows that the other prisoners think logically as well. Now, if X doesn’t answer the question for some time, Y would infer that since X is not able to answer the question, Y and Z must be having hats of different color on their heads. Hence, Y would be able to answer the question after looking at color of hat on Z’s head. If Z has a white hat on his head, Y would answer black, else white. There are five persons. Out of these five, only one is the truth teller and the remaining four are togglers i.e. But on being asked again, they will switch i.e. You need to ask only two questions to determine who the truth teller is. You can ask both the questions from the same person or ask one question each from two different people. How will you determine who is the truth teller? Are you the truth teller?. If the response to this question is Yes, then that person can be either a truth teller or a toggler who is lying. Who is the truth teller? If the picked person is the truth teller, his response to second question would be I am the truth teller. Otherwise, if the picked person is a toggler who lied to first question, he would have to tell truth for the second question and point to the truth teller. Else if the response to first question is No, then that person is a toggler who is telling the truth. Now, since the toggler has told the truth once, he would lie to second question. Who is not the truth teller?, and you will find out the truth teller. There are 100 prisoners in 100 different prisons. There is a bulb in each prison which is controlled by a switch outside that prison. Initially bulbs in the all the prisons are glowing. Would toggle in first iteration only. Hence, we see that out of first ten prisons, only prison 1, 4 and 9 would have bulb switched off after 100 iterations. This gives hint that squares of a number are the ones with off multiples and hence we can extend this logic. Which bulb will glow brighter and why? The bulbs are in series so the amount of current flowing through each is same. One door leads to heaven and the other door leads to hell. One guard always tells the truth and the other guard always lie, but you don’t know which one is honest and which one is liar. Given that you can only ask one question from one of them, what would your question be in order to find the way to heaven? ’ If I ask the other Guard about which door leads to heaven, what would he tell me? The door that the Guard specifies will lead to hell. Other door would lead to heaven. This is due to the fact that if you end up asking this question from the Guard who always tells the truth, he would point you to the door that leads to hell as he knows that the other guard would lie and would point you to the door that leads to hell. On the other hand, if you end up asking this question from the Guard who always lies, he would lie and point you to door to hell. You have one person working for you for exactly seven days. You have a gold bar to pay him. The gold bar is segmented into seven connected pieces. You must give the person a piece of gold at the end of every day. You can make only two cuts to the gold bar. Where would be these two cuts to allow you to pay the worker 1/7th gold bar each day? It’s dangerous to cross the bridge without a touch. The bridge can support only two people at a time. What is the shortest time required for all four of them to cross the bridge? F13, S15, T17, T19, S21, M23, __? Monday 23rd Next date in the series would be 25th and day would be Wednesday. Hence, the answer would be W25 . Two hundred people line up to board a plane with 200 seats. If Jack sits on his seat, Jill would find her seat unoccupied and if Jack sits on Jill’s seat, Jill would find her seat occupied. Let us now consider all 200 seats. Let’s assume Jack sits on the seat belonging to 35th person in the line. Persons 2 to 34 will sit on their own seats, and when person 35 comes in, he can sit either on the seat belonging to Jack or some random seat. If person 35th sits on Jack’s seat, Jill will find her seat. Two old friends, A and B, meet after a long time. I got married and now I have three kids. How old are your kids? Product of their ages is 72 and the sum of their ages is the same as your birth date. But I still don’t know. My eldest kid just started taking piano lessons. How old are Bill’s kids? Now, as A is not able to find their age from this data, it means that there are two or more sets with same sum. There is a triangle and on it are 3 ants, one on each corner, and they are free to move along the sides of the triangle. What is probability that the ants will collide? It is given that ants can move only along the sides of the triangle in any direction. 8.3 Lateral Thinking Lateral Thinking puzzles are sort of hybrid between puzzles and stories. In each puzzle, clues/hints to a specific scenario are given. Puzzle solver needs to fill in the details to complete the scenario. These puzzles are usually inexact and may have more than one possible answer. This category of puzzles teaches a candidate to check his/her assumptions about any situation. A man lives on the tenth floor of a building. Every day he takes the elevator to go down to the ground floor to go to work. When he returns, he takes the elevator to the sixth floor and walks up the stairs to reach his apartment on the tenth floor. When there are other people in the lift, he goes to tenth floor directly. He hates walking, so why does he walk from sixth floor to tenth floor every day? Six people each take one of the eggs. How could it be that one egg is left in the basket? The last person took the basket with the last egg still inside. There is a flash of light and a man dies. Man is struck by lightning. A hunter aimed his gun carefully and fired. Seconds later, he realized his mistake. And Minutes later, he was dead. It was winter timeframe, and the hunter fired the gun near snowy cliff that started an avalanche. An avid bird watcher sees an unexpected bird. Soon, they were both dead. Avid bird watcher is sitting in an aeroplane and sees the bird getting stuck into the engine of aeroplane, leading to a plane crash. How could a baby fall out of a 27 story building on the ground and live? The baby fell out of a ground floor window even though the building has 27 floors. Non Technical and Behavioral Questions Behavioral interview forms a key part of hiring process. It’s very important to do well in this section. Having strong technical skills alone won’t suffice as you are usually expected to work as part of a team. Behavioral skills form an important part of work culture of any company and hence this section is usually taken very seriously by recruiters. Performing great in this section with poor technical skills may not fetch candidate a job, but performing bad in this section can definitely cost candidate a job. Answer to questions in this section would be individual specific. There are no right or wrong answers for these questions. Since answers would be different for different individuals, it’s not possible for us to provide answers for these questions. However, Best answers to these questions would be the ones that reflect your actual thought process and are truthful. Being open about your aspirations, strengths and weakness always help. Try avoiding tailor made answers and be honest. Tell me something about yourself. What are your strengths and weaknesses? Why do you want to work for this job you are being interviewed for? What are your short term and long term career goals? Why should we hire you? What kind of work would you want to do if you join us? How would your present Manager/ Boss describe you? How do you deal with difficult personalities/peers/ subordinates /seniors? What’s your favorite programming language? Give an example of a time you faced a conflict while working in a team. How did you handle it? We all make mistakes we wish we could take back. Tell about a time you wish you had handled a situation differently with a colleague. Tell about a time you needed to get information from someone who wasn’t very responsive. Tell about a time you failed. How did you deal with this situation? Tell about a time you were under a lot of pressure. How did you get through it? Tell about a time your responsibilities got overwhelming. Give an example of a time when you were able to successfully persuade someone to see things your way at work. Tell about your proudest professional accomplishment. Describe a time when you saw some problem and took the initiative to correct it rather than waiting for someone else to do it. Are you a leader or a follower? If I call your boss right now and ask him about an area you could improve on, what would he say? Can you explain this gap in your employment/educational history? Tell about a time when you disagreed with your boss. Tell about a time when you did something wrong. How did you handle it? Have you ever had a difficulty with a supervisor? How did you resolve the conflict? If there were two things you could have changed about your present job, what would those be? What do you like the most about your present job? Describe a situation when your work was criticized . How did you handle it? Do you have any plans for higher/further studies? Have you been interviewed somewhere else also?