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A weighted coin with the probability of showing a head is 2 3 is tossed. If head appears, then a number is selected from the first 20 natural numbers otherwise a number is selected from the first 9 natural numbers. The probability of getting an even number is

Options

  1. A1 2
  2. B13 27
  3. C10 27
  4. D5 13

Correct answer

B. 13 27

Step-by-step solution

P H = 2 3 , P T = 1 3 A = the selected number is an even number P A = P H P A H + P T ⋅ P A T = 2 3 × 10 20 + 1 3 × 4 9 = 1 3 + 4 27 = 13 27

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