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COMEDK · Maths · 36. Probability

In an entrance test, there are multiple choice questions. There are four possible answers to each question of which only one is correct. The probability that a student knows the answer to a question is \(90 \%\). If he gets the correct answer to a question, then the probability that he was guessing is

  1. A \(\dfrac{36}{37}\)
  2. B \(\dfrac{1}{37}\)
  3. C \(\dfrac{1}{9}\)
  4. D \(\dfrac{37}{40}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\dfrac{1}{37}\)

Step-by-step Solution

Detailed explanation

Let \(K\) be the event that the student knows the answer and \(G\) be the event that the student guesses the answer. Let \(C\) be the event that the student gets the correct answer. Given \(P(K) = 0.9\) and \(P(G) = 1 - 0.9 = 0.1\). If the student knows the answer, the…