Estimation and scale: Fermi problems

An estimate is not a guess. It is the result of a rational procedure.

Learning objective Make models using imagination and three techniques:

  • Make oversimplifying assumptions
  • Break big problems into smaller problems
  • Make estimates or even guesses to solve the smaller problems.

Some tips

  • Ask: “What information would help me solve the problem?”
  • Use rough data from readily available sources
  • When in doubt, guess to nearest power of ten (logarithmic scale)

Before class

In class