### Puzzle Questions for Interview

**Puzzle 1**

Rearrange the letters of NEW DOOR to make one word.

**Answer**: ONE WORD.

[Source]

**Puzzle 2**

There are three women in swim suits. Two are sad, and one is happy. The sad women are smiling. The happy women is crying. Explain.

**Answer**: The interviewers who use questions like this probably consider them to be fun. This demonstrates the relativity of fun. The intended answer to the question above is, "They're beauty contestants." [Source: Are You Smart Enough to Work at Google? by William Poundstone]

**Puzzle 3**

You have three boxes, one holding two black marbles, one holding two white marbles, and the third holding one black marble and one white marble. The boxes are labeled for the marble colors—BB, WW, and BW—but someone has switched the labels so that every box is now incorrectly labeled. You take out ONE marble only—and from that, you can correctly say which marbles are in which box. How?

**Answer**: You can learn the contents of all three boxes by drawing just ONE marble. The key to the solution is your knowledge that the labels on all three of the boxes are incorrect. You must draw a marble from the box labeled 'black-white'. Assume that the marble drawn is black. You know then that the other marble in this box must be black also, otherwise the label would be correct. Since you have now identified the box containing two black marbles, you can at once tell the contents of the box marked 'white-white': You know it cannot contain two white marbles, because its label has to be wrong; it cannot contain two black, for you have identified that box; therefore it must contain one black and one white. The third box, of course, must then be the one holding two white marbles. You can solve the puzzle by the same reasoning if the marble you draw from the 'black-white' box happens to be white instead of black. The reader is encouraged to analyze the solutions after this draw. [Source]

**Puzzle 4**

A man rides into town on Friday, stays three days, and leaves on Friday. How does he do this?

**Answer**: "Friday" is the name of the horse. [Source]

**Puzzle 5**

If eight men can dig 16 holes in thirty-two days, how long will it take four such men to dig eight holes of the same size?

**Answer**: 32 days.

[Source] [Source 2]

**Puzzle 6**

What’s the next line?

1 1 1 2 1 1 2 1 1 1 1 1 2 2 1

**Answer**: 312211

[Source] [Source 2]

**Puzzle 7**

Which of the following sentences is correct?

Nine and five are thirteen.

or

Nine and five is thirteen.

**Answer**: None of the above is correct as nine and five is 14.

[Source]

**Puzzle 8**

Two mothers and two daughters went to lunch. The meal for each came to $1.10. The total bill for all the meals came to $3.30. How did this happen?

**Answer**: There were 3 people at lunch: grandmother, mother and daughter. [Source]

**Puzzle 9**

The amount of water in a tank doubles every minute. The tank is full in an hour. When was the tank half full?

**Answer**: 59. [Source]

**Puzzle 10**

A man works on the 10th floor and always takes the elevator down to ground level at the end of the day. Yet every morning, he only takes the elevator to the 7th floor and then walks up the stairs to the 10th floor, even when in a hurry. But he will go all the way to the 10th floor when others are in the elevator with him or on a rainy day. Why?

**Answer**:

He is too short to reach the "10" button. But when others are with him, he can ask them to push the button for the 10th floor. And on a rainy day he has an umbrella, so he can push the button using that. [Source]