Logical Interview Questions With Sample Answers

By Indeed Editorial Team

Updated 28 July 2022

Published 30 August 2021

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Logical interview questions are questions that allow recruiters to see your thought processes. Recruiters ask these questions to understand a potential employee's personal logic and how they deal with complex information. Understanding what types of logical interview questions to expect during an interview can help you feel more prepared and ready to give a competent answer. In this article, we explain the main logical interview questions to expect in an interview and give example answers to some of the most common questions.

Related: 71 good interview questions to ask candidates

What are logical interview questions?

Logical interview questions involve solving brainteasers or some type of riddles to show the interviewer your critical thinking, problem-solving and analytical skills. Logic questions for interviews can assess these skills and gauge the way you ask for information, use resources and work under pressure.

What are the main types of logic questions?

Logic questions usually fall into one of these three categories:

1. Riddles

A riddle is a question that has a double meaning or particular phrasing that usually has a surprising and unique answer. With riddles, the correct answer is often not the most important aspect. The interviewer asks these types of questions to assess your ability to think creatively, problem-solve with unique approaches and use your critical thinking skills to create solutions.

Related: 6 Brain Teaser Interview Questions and How to Answer Them

2. Numeracy problems

Numeracy problems allow you to show your understanding of mathematical working, like finding probability or using deductive and inductive reasoning to solve a problem. An interviewer poses numeracy problems to better gauge your analytical and problem-solving skills. Again, the process you used to come up with a solution can be more important than arriving at the correct answer.

Related: Numeracy skills: examples and jobs that require them

3. Finding amounts

Finding amounts questions are like numeracy problems. These questions require you to find amounts in a word problem. These questions can help the interviewer better understand how you approach unfamiliar scenarios and solve problems. Typically, these questions can have a specific answer, and for some interviewers, finding the correct answer may be just as important as how you got there.

Related: Transferable Skills: Definitions and Examples

Interview logic questions and example answers

Here are some examples of logic questions with sample answers that you can use to help during your next interview:

Fathers and sons

Two fathers and two sons eat eggs for breakfast. They ate three eggs, and each person had an egg. How is this possible?

Example answer: 'Although the riddle makes it appear that there were four people present, there were only three eggs and each person ate an entire egg, so there were only three people present at breakfast. This is possible because somebody can be both a father and a son. A son can be both a son and a father, while a father can also be someone's son. I believe there is a man, his father and the man's grandfather at breakfast. There are two sons, the man and his father, and two fathers, the father and the grandfather.'

Four names

Beth's mother has four children. The first child's name is Spring, the second child's name is Summer, and the third child's name is Autumn. What is the fourth child's name?

Example answer: 'The fourth child's name is Beth. Beth is the first name mentioned. It's her mother's name we do not know in this situation.'

The farmer, the fox and the chicken

A farmer needs to cross the river with his fox, his chicken and a bag of corn. The boat can only fit the farmer and one other thing at a time. The problem is, the fox and the chicken are both hungry, so if he leaves the fox and chicken together, the fox might eat the chicken. If he leaves the chicken and corn together, the chicken might eat the corn. How can the farmer get everyone across the river safely?

Example answer: 'The farmer should cross with the chicken first, and then he can go back for the fox. When he arrives at the other side to drop off the fox, he can take the chicken back with him to get the corn. The farmer drops off the chicken and transports the corn to the other side of the river. Finally, the farmer goes back for the chicken and continues to the other side of the river with nothing eaten.'

Forecasting rain

You are boarding a train from Cambridge that is travelling to London. You want to know what the weather is like in London, so you phone three friends who currently live in London. There is a 2/3 chance that each friend is telling you the truth and a 1/3 chance that they are telling you a lie. All 3 friends report it's currently raining in London. What is the probability that it's actually raining in London?

Example answer: 'Since all three friends are currently living in London, only one friend needs to be telling the truth for there to rain in London. First, I would calculate the chance that they are all lying but multiplying 1/3 by 3. That comes to a 1/27 chance that they're all lying to me. That means there's a 26/27 that at least one friend is telling the truth. Since I only need one friend to be telling the truth, that comes to a probability of 26/27, or 96%, that it is raining in London.'

Three light bulbs

You are standing in a room with three light switches. The switches all correspond to three different light bulbs in an adjacent room that you cannot see. With all the light switches starting in the off position, how can you find out which switch connects to which light bulb?

Example answer: 'I would turn on the first switch and let it stay on for a few minutes. Then, I'd turn the first switch off and turn the second switch on for a minute. I'd switch it off and then check the room. The warmest bulb would be the first switch. The slightly warm bulb would be the second. The cold bulb would be the third.'

Rolling the dice

If I roll two dice, what is the probability that I will get two two's on the second roll?

Example answer: 'The chance of rolling a two on a six-sided dice is 1/6. For two dice, I'd still have a one in six chance of rolling a two for each, so I'd multiply both probabilities to get the final probability of rolling two twos: 1/6 x 1/6 = 1/36. So, the probability of rolling two twos is one in 36.'

Stacking pennies

How many pennies stacked on top of each other do you need to reach the top of the Empire State Building?

Example answer: 'First, I need to know how tall the Empire State Building is and the thickness of a penny when it's laying flat. Let's say one penny is 2mm high. I can divide the height of the building by the height of the penny to get the number of pennies I'll need to stack.'

Snail on the wall

A snail is trying to climb a 30-metre garden wall. Every hour the snail climbs up 3 metres but then slides down 2 metres. If this pattern continues, when will the snail reach the top of the wall?

Example answer: 'First, to find the total amount the snail has climbed in an hour, I take away two metres per hour that the snail slips. This gives the snail one metre per hour of climbing, which results in 27 hours. Assuming the snail doesn't fall in the next hour, that's three more metres to reach the top at 30 metres high. However, for every 3 metres the snail gains, it falls, so subtracting 2 metres for slipping during the last hour results in 28 hours spent climbing.'

Ping pong balls on a plane

How many ping-pong balls can you fit into a Boeing 747?

Example answer: 'To reach this answer, I need to know some more information before I make exact calculations. First, I need to know the volume of a ping pong ball, as well as the volume inside a Boeing 747. Knowing this information, I can then divide the volume of the plane by the volume of one ping pong ball. This results in an approximate amount of ping pong balls that would fit inside the plane.'

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