Question: A marble shop contains 5 blue marbles, 5 red marbles, and 5 green marbles. If 2 marbles are purchased at random from the shop, what is the probability that the 2 marbles will be of the red?
Options:
(A) 5/15
(B) 2/21
(C) 20/15
(D) 5/210
(E) 4/14 Random thoughts:
Of the 15 marbles we are wanting red:
Probability of choosing 1st red marble: 5/15
Probability of Choosing 2nd red marble: 4/14
Multiply and you get 20/210 simplified to 2/21 The final answer: (B).