## Interview Puzzles

###### 2 years ago Lalit Bhagtani 0

Interview Puzzles and logical questions are very important part of any selection process for a job interview. This series is written to help those guys who are preparing for the job interview. The puzzle is explained first and then the optimal solution for that puzzle is given. It is highly recommended that you try to solve the puzzle on your own and then look for a solution.

**Interview Puzzles :- **

This post is written to be an index of interview puzzles, list of all interview puzzles are as follows :-

### 8 Balls Weight Puzzle

**Interview puzzles :-** You have given a two-arm balance scale and 8 identical looking balls. One of the balls is heavier than rest of the 7 balls, which all are of equal weight. You have to find out the heavier ball by using two arm balance scale a minimum number of times.

### 9 Balls Puzzle

**Interview puzzles :-** You have given a two-arm balance scale and 9 identical looking balls. One of the balls is of different weight(heavier/lighter) than rest of the 8 balls, which all are of equal weight. You have to find out the different weight(heavier/lighter) ball and identify whether the ball is heavier or lighter by using two arm balance scale, the minimum number of times.

### Rope Bridge Puzzle

You have given two ropes of varying thickness both are of different density, different width, and different length. Each rope burns in 60 minutes. You have to measure 45 minutes using only these two ropes. Note that you can not cut one rope in half because the ropes are non-homogeneous and you can not be sure how long it will burn.

### 3 Ants and Triangle Puzzle

There are 3 ants sitting at the three different corners of an equilateral triangle. Now each ant randomly picks a direction and starts moving along the edge of the triangle. What is the probability that none of the ants collide with each other?

### Bridge Crossing Puzzle

Four people need to cross a rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for 17 minutes. The bridge is too dangerous to cross without a flashlight, and it’s only strong enough to support two people at any given time. Now each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the slowest camper takes 10 minutes to cross. How can the campers make it across in exactly 17 minutes?

### Heaven or Hell Puzzle

You are standing before two doors. One leads to heaven and the other one leads to hell. There are two guardians, one by each door. You know one of them always tells the truth and the other always lies, but you don’t know who is the honest one and who is the liar.

### 10 Coins Puzzle

There are 10 coins placed on the table, 5 coins head up and 5 coins tails up. You are blindfolded and are allowed to touch the coins but you can’t tell which one heads up or tails up just by feeling and you can flip the coins any number of times. How do you make two piles of coins each with the same number of heads up?

### 3 Mislabeled Boxes Puzzle

**Interview puzzles :-** You have given 3 boxes, One contains the red color ball, another contains the blue color ball and the third one contains the green color ball. All boxes are mislabelled, which means blue label box does not contain the blue color ball, red label box does not contain the red color ball and green label box does not contain the green color ball.

### Gold Bar Puzzle

**Interview puzzles :-** You have hired a person for seven days to work on your house and you have agreed to pay him a gold bar as a compensation. The gold bar is divided into seven pieces and is connected with each other like a chain. You have to give him a piece of gold at the end of everyday work. What and where are the minimum number of cuts to the chain of gold bar pieces will be made, So that you can pay him a piece of gold every day?

### Genie with C Hats Puzzle

**Interview puzzles :-** There are **N **number** **of men and one genie on a deserted island, A genie gathers all the men and put the hat on **C** number of men’s head, such that one man has only one hat on his head. The hat has some magical powers, hat cannot be seen by the man who is wearing it, but all the other man can see it, whether they are wearing any hat or not. To remove the hat, men (only those who has a hat on his head) must dip themselves underwater at exactly midnight. How many days, it will take the men to remove all the hats?

### 25 Horses 5 Tracks Puzzle

**Interview puzzles :-** You have given one horse race track and 25 horses. In one race, only(maximum) 5 horses can run together. What is the minimum number of races that are required to find 3 fastest horses?

### Red and Blue Marbles Puzzle

**Interview puzzles :-** You have given 50 red marbles, 50 blue marbles and two empty jars. You have to put all the 100 marbles into the jars, such that when you randomly pick one marble from any of the jar, probability of it’s being a red color marble is maximum. How will you do that ?

### 100 People in a Circle Puzzle

**Interview puzzles :-** There are 100 people standing in a circle. Person standing at 1st position kills next person ( i.e. the person standing at 2nd position ) and gives sword to next to next person ( i.e. the person standing at 3rd position ). Which person survives in the last ?

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