A sack of 30 marbles total contains 10 red marbles, 8 white marbles, 9 blue marbles and 3 green marbles. One marble is removed and examined at a time and placed back into the bag until a white marble is successfully removed. What is the probability that a white marble will be removed on the 2nd try or better? Pick one:  A) 1/3  B) 3/8  C) 4/9  D) 7/12  E) 11/15
Favorable case = a white marble is removed in the 2nd try or later.   Unfavorable case = a white marble is removed on the first attempt.   Probability = Favorable outcomes / Total out comes   Also probability = 1-(Unfavorable outcomes / Total out comes)   Unfavorable case: probability of apple picked in first extraction = 8/30   Total Unfavorable Probability = 4/15   i.e., Favorable Probability = 1 - (4/15) = 11/15   Answer Option: 11/15
<result>E</result>
A sack of 30 marbles total contains 10 red marbles, 8 white marbles, 9 blue marbles and 3 green marbles. One marble is removed and examined at a time and placed back into the bag until a white marble is successfully removed. What is the probability that a white marble will be removed on the 2nd try or better?