Multiple choice

An urn contains 10 white balls numbered 1 to 10. A ball is to be selected at random and placed aside. What is the probability that we get a ball numbered '3' in first three turns?

  1. 3/10

  2. 1/30

  3. 121/360

  4. None of these
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A Correct answer
Explanation

The probability of picking the ball numbered 3 in any of the first three turns is 1 - P(not picking 3 in 3 turns). P(not picking 3) = (9/10) * (8/9) * (7/8) = 7/10. So, P(picking 3) = 1 - 7/10 = 3/10.

AI explanation

The probability of getting the ball numbered 3 on the first draw is 1/10, on the second draw is (9/10) times (1/9) which is 1/10, and on the third draw is (9/10) times (8/9) times (1/8) which is also 1/10. By the addition rule of probability for mutually exclusive events, the total probability is the sum of these individual probabilities: 1/10 plus 1/10 plus 1/10. This results in a total probability of 3/10.

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