Ex 13.3, 13 (MCQ) - Chapter 13 Class 12 Probability
Last updated at August 13, 2026 by Teachoo
Bayes theorem
Example 16
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Chapter 13 Class 12 Probability
Concept wise
- Conditional Probability - Values given
- Conditional Probability - Statement
- Multiplication rule of probability
- Independent events
- Basic Probability
- Theorem of total probability
-
Bayes theorem
- Random Variable - Defination
- Probability distribution
- Mean or Expectation of random variable
- Variance and Standard Deviation of a Random Variable
- Bernoulli Trials
- Binomial Distribution
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Transcript
Ex 13.3, 13 Probability that A speaks truth is 4/5 . A coin is tossed. A reports that a head appears. The probability that actually there was head is (A) 4/5 (B) 1/2 (C) 1/5 (D) π/πLet E : A speaks truth F : A Lies H : head appears on the toss of a coin We need to find the Probability that head actually appears, if A reports that a head appears i.e. P(E|H) P(E|H) = "P(E) . P(H|E) " /"P(F) . P(H|F) + P(E) . P(H|E)" P(E) = Probability that A speaks truth = π/π P(H|E) = Probability that head appears, if A speaks truth = π/π P(F) = Probability that A lies = 1 β P(E) = 1 β 4/5 = π/π P(H|F) = Probability that head appears, if A lies = π/π Putting values in formula, P(E|H) = (4/5 Γ 1/2)/(1/5 Γ 1/2 + 4/5 Γ 1/2) = (1/5 Γ 1/2 Γ 4)/(1/5 Γ 1/2 [1 + 4]) = 4/5 Therefore, required probability is 4/5 β΄ A is the correct answer
