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- Suppose we put eight white and two black balls into a bag and then draw forth the balls one at a time. If we repeat this experiment many times, which draw is most likely to produce the first black ball?
Most people answer 4, but in fact the first black ball is most likely to appear on the very first draw:
geneusutwerk · 3234 days ago · link ·
Well it is interesting, I assume that the phrasing is important "the first black ball". So if you say the 2nd draw, and they've already drawn one on the first one then you lose. Your probability of drawing a black ball in the first draw is 2/10 = .20
The probability of drawing your first black ball on the second draw is the probability of drawing a white ball first and then a black ball = (8/10)(2/9) = 0.178
Probability of drawing your first black ball on the third turn = (8/10)(7/9)*(2/8) = 0.156