Are you smart enough to work for Google?

Here are some interview questions asked at Google and Microsoft. Some of these are supposed to generate a specific answer, some are asked to gauge how you estimate, analyse and approach the seemingly impossible problems.

Post some of your answers in the comments, but no cheating. I’ve figured out number 10, but would be interested in your solutions.Number 11 has me puzzled, and if you can do number 13, then I think you own Google. And I would love to hear your answers to number 16 and number 17.

(All of the questions below were harnessed from websites and blogs about Google and Microsoft, and all were supposedly asked of someone, at some point. But no guarantees.)

1. How many golf balls can fit in a school bus?

2. How much should you charge to wash all the windows in Seattle?

3. Explain a database in three sentences to your eight-year-old nephew.

4. How many times a day do a clock’s hands overlap?

5. You have to get from point A to point B. You don’t know if you can get there. What would you do?

6. Imagine you have a closet full of shirts. It’s very hard to find a shirt. So what can you do to organise your shirts for easy retrieval?

7. In a country in which people only want boys, every family continues to have children until they have a boy. if they have a girl, they have another child. if they have a boy, they stop. what is the proportion of boys to girls in the country?

8. You are at a party with a friend and 10 people are present including you and the friend. your friend makes you a wager that for every person you find that has the same birthday as you, you get $1; for every person he finds that does not have the same birthday as you, he gets $2. would you accept the wager?

9. How many piano tuners are there in the entire world?

10. You have eight balls all of the same size. Seven of them weigh the same, and one of them weighs slightly more. How can you find the ball that is heavier by using a balance and only two weighings?

11. You have five pirates, ranked from five to one in descending order. The top pirate has the right to propose how 100 gold coins should be divided among them. But the others get to vote on his plan, and if fewer than half agree with him, he gets killed. How should he allocate the gold in order to maximise his share but live to enjoy it? (Hint: One pirate ends up with 98% of the gold.)

12. One train leaves Los Angeles at 15mph heading for New York. Another train leaves from New York at 20mph heading for Los Angeles on the same track. If a bird, flying at 25mph, leaves from Los Angeles at the same time as the train and flies back and forth between the two trains until they collide, how far will the bird have travelled?

13. Pairs of primes separated by a single number are called prime pairs. Examples are 17 and 19. Prove that the number between a prime pair is always divisible by six (assuming both numbers in the pair are greater than six). Now prove that there are no “prime triples”.

14. Imagine you are standing in front of a mirror, facing it. Raise your left hand. Raise your right hand. Look at your reflection. When you raise your left hand your reflection raises what appears to be his right hand. But when you tilt your head up, your reflection does too, and does not appear to tilt his/her head down. Why is it that the mirror appears to reverse left and right, but not up and down?

15. How would you build an alarm clock for deaf people?

16. If Microsoft told you we were willing to invest $5-million in a start-up of your choice, what business would you start? Why?

17.If you are going to receive an award in five years, what is it for and who is the audience?

18. Suppose you go home, enter your house/apartment, hit the light switch, and nothing happens — no light floods the room. What exactly, in order, are the steps you would take in determining what the problem was?