• P(A) = The probability of a particular outcome A occurring.
  • P(flipping a head) = .5
• 0 ≤ P(A) ≤ 1
  • The probability of an outcome must always be between 0% and 100%
• P(not A) = 1 – P(A)
  • P(not flipping a head) = 1 - .5 = .5
• The sum of all possible events equals to 1.