your odds of correctly guessing the outcome of a flipped coin are 1 in 2, but your odds of guessing correctly twice in a row are only 1 in 4 —
your odds of correctly guessing the outcome of a flipped coin are 1 in 2, but your odds of guessing correctly twice in a row are only 1 in 4 —
probability:106
p ( a  or  b ) = p ( a ∪ b ) = p ( a ) + p ( b ) − p ( a ∩ b ) = p ( a ) + p ( b ) − 0 = p ( a ) + p ( b ) {\displaystyle p(a{\mbox{ or }}b)=p(a\cup b)=p(a)+p(b)-p(a\cap b)=p(a)+p(b)-0=p(a)+p(b)} for example, the chance of rolling a 1 or 2 on a six-sided die is p ( 1  or  2 ) = p ( 1 ) + p ( 2 ) = 1 6 + 1 6 = 1 3 .