updated on 2012-03-03

Try to answer the following questions, not by giving the exact answer, but by giving a range for which you are 90% sure that contains the correct answer. For example:

1. How many member states did United Nations have in 2010?

Suppose you think that the answer is somewhere around 150. Now, you just need to write a range within which you are 90% sure the correct number will be. For example, confident people would answer with "140 — 170". If you're not that sure, it would be better to answer "100 — 200". Answering "0 — 999 999" would be an exaggeration, because you need to aim for a 10-percent risk that you won't answer correctly. (By the way, the exact number is 193.)

These are not trick questions. No need for looking online or asking other people — if you are unsure about your answer, just write in a wider range. If you don't have any idea what would be the right answer, try to logically determine in what range it should be, but leave a 10% chance of getting it wrong. And take as much time as you wish.

Here are the questions:

1. What is the greatest known ocean depth on Earth? 10911 m
2. How many stone blocks were used to build the Great Pyramid of Giza? 2300000 blocks
3. In how many of his movies does Alfred Hitchcock make a cameo appearance? 39 times
4. How long is the Trans-Siberian Railway? 9260 km
5. What year was Beethoven born? 1770
6. What year did Michelangelo finished his statue of David? 1504
7. How long is the river Nile? 6650 km
8. What's the maximum takeoff weight of Boeing 747-400? 397 tons
9. How long is the gestation period (pregnancy) of an African elephant? 22 months
10. What is the mean diameter of the Moon? 3475 km

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