Tom and Marry each have a bag of marbles, each of which contains 4 Red marbles, 10 blue marbles, and 6 yellow marbles. If Tom and Marry each select one marble from their respective bags, what is the probability that either Tom or Marry select a blue marble?
Choices.
A) 1 / 7  B) 2 / 4  C) 3 / 4  D) 1 / 8  E) 1 / 16

Rationale: probability that either selects a red marble , p ( either ) = 1 - probability that neither selects a blue marble , p ( neither ) probability that tom selects non blue = 10 c 1 / 20 c 1 = 1 / 2 probability that marry selects non blue = 10 c 1 / 20 c 1 = 1 / 2 = > p ( either ) = 1 - ( 1 / 2 * 1 / 2 ) = 1 - 1 / 4 = 3 / 4 . c )
Answer: C