A List of Common Interview Puzzles with Answers

Interviewers for technical and programming positions love asking puzzles. A good puzzle reveals so much about the applicant. It shows his approach, his demeanor and his basic abilities to solve a problem. It can also reveal the applicant’s sense of humor and is a great ice-breaker. This is a list of common interview puzzles with answers. Some of the answers are also in the video format.

Blindfold Coin Game Strategy | Yahoo Interview Puzzle

You are blindfolded and you can not see.

There are 10 coins on the table.

5 of these coins are heads up, and the other 5 are tails up.

You can touch these coins but you can not determine which side is, heads up, or tails up, by touching or feeling them.

Your goal is to, make 2 groups of coins, such that, each of these groups, have the same number of heads up coins. You can flip the coins any number of times! 

What will be your strategy?

25 Horses | Google Interview Puzzle with Answer

Given 25 horses, find the best 3 horses, with the minimum number of races.

Each race can have only 5 horses.
You don’t have a timer to time the races.

What is the minimum number of races required to find the best 3 horses?

3 Mislabeled Jars | Apple Interview Puzzle with Answer

You love candy and you are given 3 opaque candy jars which contain candies that are either orange or pink. One of them is labeled ‘Orange’, one ‘Pink’ and one ‘Orange + Pink’. Orange jar has only orange candies, pink jar has only pink candies and ‘Orange + Pink’ jar has both orange and pink candies. But, all three of them have been mislabeled. You can take out one candy at a time.

What is the minimum number of candies that you need to take out to label all 3 jars correctly?

Red & Blue Marbles | Google Interview Puzzle with Answer

You have 50 red marbles, 50 blue marbles and 2 jars. All 100 marbles should be placed in either of the jars. One of the jars is chosen at random and then one marble will be chosen from that jar at random.

How would you maximize the chance of drawing a red marble? What will be the probability of doing so?

Box with Defective Balls | Microsoft Interview Puzzle with Answer

You have 10 boxes that contains balls from different manufacturers, with each of the ball weighing 10 grams precisely. One of the manufacturer made a mistake and its balls weigh 9 grams each.
You don’t know which box contains the defective balls. You have been provided with an electronic weighing machine but you are allowed to use it only once.

How will you find out, which box contains the defective balls?

Bugs on a Triangle | Microsoft Interview Puzzle with Answer

3 bugs problem was made famous by being frequently asked in Microsoft interviews. The problem goes like this.
There is an equilateral triangle and three bugs are sitting on the three corners of the triangle. Each of the bugs picks up a random direction and starts walking along the edge of the equilateral triangle.
What is the probability that none of the bugs crash into each other?

Samsung Interview Puzzle | Age of Daughters

Sundar makes a visit to Satya’s house. They were not in touch for a long time. As they get talking, Satya keeps referring to his daughters. From his talk Sundar is able to guess that he has 3 daughters. After a while, Sundar asks the age of his daughters.

Satya doesn’t want to make it too easy for Sundar so he gives Sundar a hint.

“The product of their ages is 72.”

Sundar thinks hard and then concludes that this is not adequate information. Satya gives Sundar another hint.

“The sum of his daughter’s ages is equal to the age of Sundar’s only son”. Sundar maintains that he still does not have sufficient information.

What is the age of Sundar’s son?

At this point, Satya gives him third hint. “His youngest daughter’s name is Anita”! Sundar immediately tells the age of his 3 daughters.

Can you now find out their ages?

Liar and Truth Teller Riddle

You are an investigating officer and you enter a city with a total of 100 truth-tellers and liars. Your mission is to find out how many of them are truth-tellers and how many are liars.

The first one you meet says,”at least 1 of us is a liar”. The second one says,”at least 2 of us are liars”. The third one says,”at least 3 of us are liars”. And so on.




The 99th one says,”at least 99 of us are liars”.

At this point you get a call from your chief and he asks,”so, how many of them are liars?”. You say,”I have no idea, chief”.

Then the 100th one meets you and says,”all of us are liars”.

You immediately call up your chief and say,”I know the answer, chief”.

Find out how which one of them are liars and which ones are truth-tellers!

Measure 4 Gallons | Amazon Interview Puzzle with Answer

You are a milkman and you have a 3 gallon milk bucket and a 5 gallon milk bucket. You also have more than adequate milk in a large tub. A customer arrives who however insist on buying exactly 4 gallons of milk.

How would you measure 4 gallons of milk with these 2 milk buckets?

8 Brothers | Samsung Interview Puzzle with Answer

There is an old house where there is no electricity, no computers or any any other gadget.

8 brothers live here.

On a Sunday morning,
First brother, is reading comics.
Second brother, is playing chess.
Third brother, is writing.
Fourth brother, is cooking.
Fifth brother, is sleeping.
Sixth brother, is cleaning house.
Seventh brother, is watering the plants.

What is the eighth brother doing?

Who will you save? Microsoft Interview Puzzle with Answer

You are driving along in your car on a wild, stormy night. It’s raining heavily, when suddenly you pass by a bus stop, and you see three people waiting for a bus.

An old lady who seems ill and needs to go to the hospital.
An old friend who once saved your life.
The perfect partner you have been dreaming about.

What will you do, knowing very well that there could only be one passenger in your car?

If you want to share any puzzle or questions asked in an interview, you can write it in the comments. Thanks in advance for sharing!

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