## Problem Definition

### Firefighter

**Situation:**

A firefighter stood on the middle rung of a ladder, spraying water on a burning house. He then climbed up 6 rungs before the heat of the flames caused him to come down 10 rungs. After some minutes he was able to climb 18 rungs to the very top of the ladder.

**Question:**

How many rungs did the ladder have?

### Bartender

**Situation:**

There are two twin old men that go into the same bar every day. The bartender at the bar hates one of the twins, but there is only one way he could tell the difference between them: The one that he hates drinks very slowly and the one that he likes drinks fast.

One day the bartender decides to kill the one that he hates. So when they came in that day he put the same amount of the drink in their cups, the same amount of ice, and the same amount of poison. When they are both done with their drinks the one that the bartender hates dies, but the one he likes lives.

**Question:**

How is this?

### Hats

**Situation:**

There are 4 people sitting in a row, trying to win a riddle.

- The one in front was wearing a red hat.
- The second from the front was wearing a blue hat.
- The third from the front was wearing a red hat.
- The last was wearing a blue hat and is blind-folded.

Each of them was informed that they are all wearing a hat, the last person is blind-folded and that there are 2 red and 2 blue hats. They can only see the persons in front of them and are not allowed to turn around and see behind them.

**Question:**

The one who guesses the color of his hat wins the prize. Who is it?

## Comments

Brain Teasers are short questions with difficult logical or creative answers. They are a good way to test your analytical skills and capacity to think out of the box. These short questions also show the interviewer your ability to elaborate on difficult tasks from the real world. Each Brain Teaser is supposed to be solved by the interviewee in about 5-10 minutes.

If the interviewee gets stuck in a brain teaser (i.e. spends more than 10 minutes), propose to go on to the next one.

## Detailed Solution

### Firefighter

29 rungs

The firefighter is standing on the middle rung. He goes up 6 rungs so he is now at M+6, he now goes down 10 rungs so he is now at M-4 he goes up 18 rungs so he is now at M+14=T. 14 rungs from the top, 14 rungs from the bottom and the middle rung. 14+14+1=29

### Bartender

The bartender puts the poison in the ice.

In the drink of the one who drank slow the ice melted, but since the other one drank fast, his ice never melted.

### Hats

It was the second person.

The first and last person cannot see other people at all, therefore it is either the third or second. The second person realized that if he and the person in front were wearing the same colored hat, the third person would be able to answer the color of his hat right away. However, since there was a long silence, then the color of his hat and the person in front must be different.