MEPX
Chapter 3 of 11All chapters
  1. 1What probability means
  2. 2Counting outcomes
  3. 3Independent events
  4. 4Dependent events
  5. 5Complements and at least one
  6. 6Adding probabilities
  7. 7Permutations and combinations
  8. 8Conditional probability
  9. 9Expected value
  10. 10Distributions in outline
  11. 11Fallacies and traps

Chapter 3 of 11

Independent events

Multiply along the and.

Multiplying

Two fair flips give four equally likely outcomes and only one is heads twice, so the chance is 1 in 4. Multiplying the separate chances gives the same answer.

  • And usually means multiply. Or usually means add.
  • Multiplying only works when one event does not change the other.

Two dice

Two dice give 36 combinations. Seven can be made six different ways, more than any other total, which is why it is the most likely sum and the basis of most dice games.