yr1 chap 5 probability

• to prove that X and Y are not statistically independent:

  • find P(X and Y)
  • find P(X) x P(Y)
  • show they are not equal
• to prove that X and Y are statistically independent:

  • find P(X and Y)
  • find P(X) x P(Y)
  • show they are equal
• to prove that X and Y are mutually exclusive:

  • find P(X or Y)
  • find P(X) + P(Y)
  • show they are equal
• to prove that X and Y are not mutually exclusive:

  • find P(X or Y)
  • find P(X) + P(Y)
  • show they are not equal
• in venn diagrams, A and B means the overlap between A and B, it is called intersection
• in venn diagrams, A or B means all of A and all of B, it is called union
• in venn diagrams, not A means everything apart from A, it is called complement