Tim Richardson's Overconfidence in decision making, an online quiz

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Self-test of Overconfidence

For each of the following ten items, provide a low and high guess such that you are 90 percent sure the correct answer falls between the two.

Your challenge is to be neither too narrow (ie, overconfident) not too wide (ie, underconfident).

If you successfully meet this challenge, your result should at be least 8 correct (94% likelihood).

You can be 99.9% sure of getting at least 6 correct ...

Source: Confident Decision Making, J. E. Russo & P. J. H. Schowmaker, 1989, Piatkus, London p 71

Question Low High Units
1. Martin Luther King's age at death

2. Length of the Nile River KM MILES
3. Number of countries that are members of OPEC

4. Number of books in the OldTestament

5. Diameter of the moon KM MILES
6. Weight of an empty Boeing 747 KG POUNDS
7. Year in which Wolfgang Amadeus Mozart was born

8. Gestation period (in days) of an Asian elephant

9. Air distance from London to Tokyo. KM MILES
10. Deepest (known) point in the oceans. METRES FEET

Question	Low	High	Units
1. Martin Luther King's age at death
2. Length of the Nile River			KM MILES
3. Number of countries that are members of OPEC
4. Number of books in the OldTestament
5. Diameter of the moon			KM MILES
6. Weight of an empty Boeing 747			KG POUNDS
7. Year in which Wolfgang Amadeus Mozart was born
8. Gestation period (in days) of an Asian elephant
9. Air distance from London to Tokyo.			KM MILES
10. Deepest (known) point in the oceans.			METRES FEET