Multiple choice

Find the chance of drawing 2 blue balls in succession from a bag containing 5 red and 7 blue balls, if the balls are not being replaced.

  1. $\dfrac{3}{13}$
  2. $\dfrac{21}{64}$
  3. $\dfrac{7}{22}$
  4. $\dfrac{21}{66}$
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C Correct answer
Explanation

Total balls = 12. P(first blue) = 7/12. P(second blue | first blue) = 6/11. P(both blue) = (7/12) * (6/11) = 42/132 = 7/22.

AI explanation

Use the multiplication theorem for dependent events to find the probability of drawing two blue balls in succession without replacement. The probability of the first blue ball is 7 out of 12, and the probability of the second blue ball is 6 out of 11. Multiplying these gives 42 divided by 132, which simplifies to 7 over 22.

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