An urn contains 5 black and 20 white marbles. They are to be drawn one at a time until all of one color has been exhausted.
What is the probability that the color of the first draw correctly predicts the first color exhausted?
(In reply to re(2): solution
Let not be confused with the wordings:
.I SAID:..........IMHO the probability you have evaluated is the probability of matching (same color) of 1st drawn with the last of same color." ;
it addresses the last i.e the exhausting one, - we do not want to continue till the end.
All in all, continuing to read in this context I maintain that
the official solution re prediction is 2/3, not 1/3.
Please read the definition of the task and revert.