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WBJEE · Maths · Probability

An urn contains 8 red and 5 white balls. Three balls are drawn at random. Then, the probability that balls of both colours are drawn is

  1. A \(\frac{40}{143}\)
  2. B \(\frac{70}{143}\)
  3. C \(\frac{3}{13}\)
  4. D \(\frac{10}{13}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{10}{13}\)

Step-by-step Solution

Detailed explanation

Total number of selections of three balls in which balls of both colours are drawn \(=2\) red balls and 1 white ball +1 red ball and 2 white balls \(\begin{array}{l} ={ }^{8} C_{2} \times{ }^{5} C_{1}+{ }^{8} C_{1} \times{ }^{5} C_{2} \\ =140+80=220 \end{array}\) \(\therefore\)…