How to get a job at Microsoft

William Poundstone shows you how to ace an interview at Microsoft. Simply be able to answer the following questions:

1. How would you weigh a jet plane without using scales?

2. Why are manhole covers round rather than square?

3. Why is it that, when you turn on the hot water in a hotel, the hot water comes out instantly?

4. How do they make M&Ms?

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

6. You have eight billiard balls. One of them is “defective”, meaning that it weighs more than the others. How do you tell, using a balance, which ball is defective in two weighings?

7. You have two jars and 100 marbles. Fifty of the marbles are red, and 50 are blue. One of the jars will be chosen at random; then one marble will be withdrawn from that jar at random. How do you maximise the chance that a red marble will be chosen? (You must place all 100 marbles in the jars.) What is the chance of selecting a red marble when using your scheme?

8. You have a three-quart bucket, a five-quart bucket, and an infinite supply of water. How can you measure out exactly four quarts?

Can you answer them?