l Chapter 5- Key concepts Mutually exclusive events Events a and b are mutually exclusive if both cannot occur at the same time that is if their intersection is em pty. In a venn diagram, mutually exclusive events are usually shown as nonintersecting areas. If intersecting areas are shown, they are empty o 2002 The Wadsworth Group
Chapter 5 - Key Concepts • Mutually exclusive events – Events A and B are mutually exclusive if both cannot occur at the same time, that is, if their intersection is empty. In a Venn diagram, mutually exclusive events are usually shown as nonintersecting areas. If intersecting areas are shown, they are empty. © 2002 The Wadsworth Group
INtersections versus unions Intersections-"Both/And The intersection of a and b and c is also written A∩B∩C All events or characteristics occur simultaneously for all elements contained in an intersection Unions- Either/Or The union of a or b or c is also written 儿UB∪C At least one of a number of possible events occur at the same time o 2002 The Wadsworth Group
Intersections versus Unions • Intersections - “Both/And” – The intersection of A and B and C is also written . – All events or characteristics occur simultaneously for all elements contained in an intersection. • Unions - “Either/Or” – The union of A or B or C is also written – At least one of a number of possible events occur at the same time. A B C A B C. © 2002 The Wadsworth Group
l Working with unions and Intersections The generalrule of addition P(a or B)= P(a+ P(B)-P(a and b) is always true. When events a and b are mutually exclusive the last term in the rule, p(a and b), will become zero by definition o 2002 The Wadsworth Group
Working with Unions and Intersections • The general rule of addition: P(A or B) = P(A) + P(B) – P(A and B) is always true. When events A and B are mutually exclusive, the last term in the rule, P(A and B), will become zero by definition. © 2002 The Wadsworth Group