If A and B are two events such that P (A) = 3/4, P (B) = 1/2 and P (A n B) = 3/8,
find P (not A and not B).	Select the correct option
A) 1 / 9  B) 1 / 8  C) 1 / 11  D) 1 / 13  E) 2 / 5

Rationale: p ( not a and not b ) = 1 - ( p ( a ) + p ( b ) - p ( ab ) ) which you might find somewhere in your text . substituting in our probabilities we get : p ( not a and not b ) = 1 - ( 3 / 4 + 1 / 2 - 3 / 8 ) p ( not a and not b ) = 1 - ( 7 / 8 ) p ( not a and not b ) = 1 / 8 . b
Answer: B