Question 1195017: There are 5 white and 3 black marbles in a basket. 2 marbles have been lost from the basket. A. What is the probability that when randomly picking out a marble it is going to be white? B. Lets say we picked out a white marble. What is the probability that one of the lost marbles is white, the other - black?
Kind thanks for the help!
Answer by ikleyn(52897)   (Show Source):
You can put this solution on YOUR website! .
There are 5 white and 3 black marbles in a basket.
2 marbles have been lost from the basket.
A. What is the probability that when randomly picking out a marble it is going to be white?
B. Lets say we picked out a white marble. What is the probability that one of the lost marbles
is white, the other - black?
Kind thanks for the help!
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In this my post, I will answer question (a), ONLY.
The initial basket state is (5W,3B).
The two lost balls are either (W,W), or (W,B), or (B,W), or (B,B).
(1) If the lost pair is (W,W), then the probability for this event is  =  .
Hence, the basket's new state is (3W,3B) with the probability .
(2) If the lost pair is (W,B) or (B,W), then the probability for this event is  =  .
Hence, the basket's new state is (4W,2B) with the probability .
(3) If the lost pair is (B,B), then the probability for this event is  =  .
Hence, the basket's new state is (5W,1B) with the probability .
In case (1), the probability to pick white marble from the basket is  .
In case (2), the probability to pick white marble from the basket is  .
In case (3), the probability to pick white marble from the basket is  .
Thus the probability to pick white marble is
 =  =  =  .
So, the ANSWER to question (a) is .
Solved.
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What is even more important than getting the answer, you learned from my post on how to solve the problem.
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