SOLUTION: A box contain 4 red balls and 3 black balls. A ball is drawn random from the box, its color is noted and is not replaced. the process is repeated until two red balls are obtained.

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Question 921937: A box contain 4 red balls and 3 black balls. A ball is drawn random from the box, its color is noted and is not replaced. the process is repeated until two red balls are obtained. If X represents the number of draws needed to get two red balls, determine P(X<3)
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
7 Balls: 4R, 3B
A ball is drawn random from the box, its color is noted and is not replaced....
If X represents the number of draws needed to get two red balls,
determine P(X<3) = P(X = 2) = P(1stR AND 2ndR) = %284%2F7%29%283%2F6%29 = 12/42 = 2/7