Weinstein, L., & Adam, J. A. (2008). Guesstimation: Solving the world's problems on the back of a cocktail napkin. Princeton, N.J.: Princeton University Press.



(Answers: the players run around 20km or 12 miles; ten million people are picking their nose (so stop it!). Everyone would fit (but uncomfortably) into a city whose land area was the size of Los Angeles. To give everyone a home would still only fill up 1% of the earth's surface)

Link to for the book