Business Stat Lecture 1 01 11 2012 Probability model for quantifying uncertainty in life Experiment action or process leading to a well defined set of outcomes outcome is not predictable Outcome possible outcomes of random experiment o Ex tossing a coin rolling pair of dice measuring person s blood pressure observe sex of newborn child Sample Space set of all possible outcomes of an experiment denoted by S N denotes collection of all natural numbers including zero o Tossing a coin S Heads Tails o Rolling dice S i j i 1 6 j 1 6 o Observe sex of newborn child S Boy Girl Event subset of possible outcomes event is said to occur is outcome of experiment is one of the members of event o An even number occurs in tossing a die E 2 4 6 o Two even numbers occur in tossing a pair of dice E i j i 2 4 6 j 2 4 6 Ex consider experiment of flipping a coin three times Sample space o By enumeration S HHH HHT HTH HTT THH THT TTH TTT o By description S i j k i j k H or T Event A that exactly one tail was observed when flipping coin three times and event B that majority of coins show heads o A HHT HTH THH o B HHH HHT HTH THH Informally used It is likely It is expected There will probably be There is a 50 50 chance DeMorgan s law Complement rule Addition rule Addition rule for disjoint events 01 11 2012 01 11 2012