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AP EAMCET202421 May 2024Evening ShiftMathematicsProbabilityActual

An urn contains 3 black and 5 red balls. If 3 balis are drawn at random from the urn, the mean of the probability distribution of the number of red balls drawn is

Options

  1. A45 28
  2. B15 8
  3. C2 5
  4. D3 2

Correct answer

B. 15 8

Step-by-step solution

Let X be number of red balls drawn. array |c|c|c|c|c| X = x & 0 & 1 & 2 & 3 P ( X = x ) & ^3 C₃ ^8 C₃ & ^5 C₁ ^3 C₂ ^8 C₃ & ^5 C₁ ^3 C₁ ^8 C₃ & ^5 C₃ ^8 C₃ array array |c|c|c|c|c| X = x & 0 & 1 & 2 & 3 P ( X = x ) & 1 56 & 15 56 & 30 56 & 10 56 array Mean =0 1 56 +1 15 56 +2 30 56 +3 10 56 = 15 8 .

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