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AP EAMCET202124 Aug 2021Evening ShiftMathematicsProbabilityActual

A man is known to speak truth 7 out of 10 times. After throwing a die with 100 faces marked 1,2,3,.., 100 on it's faces, the man reports that he got a prime number on the die. What is the probability that it is actually a prime?

Options

  1. A5 16
  2. B7 16
  3. C11 16
  4. D10 16

Correct answer

B. 7 16

Step-by-step solution

Consider the events A= Probability that prime number occur B= Probability that prime number does not occur E= prime number occur when man reports 25 prime number from 1 to 100 P(A)= 25 100 = 1 4 P(B)= 75 100 = 3 4 P(E / A)= 7 10 , P(E / B)= 3 10 Required probability P(A / E)= 1 4 7 10 1 4 7 10 + 3 4 3 10 = 7 16

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