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Heather and Isabelle play a two-person game which is won by the first person to accumulate 10 points. At each turn Heather gains a point with probability of 2/3. If she doesn't get a point then Isabelle gets a point. Isabelle is now ahead 9 to 6. What is the probability that Isabelle will win? Express your answer as a common fraction.

 Jun 24, 2020
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Is isabella where to win, she would need to get 4 more point. The probability of her getting a point is 1/3, so if she needs to get 4 points, the probability would be 1/3 * 1/3 * 1/3 * 1/3 =  (1/3)^4 = 1/81. So the answere is 1/81.

 Jun 25, 2020
edited by ItzMe  Jun 25, 2020

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