Question

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

• A. \( \frac{36}{37} \)
• B. \( \frac{1}{9} \)
• C. \( \frac{1}{37} \)
• D. \( \frac{37}{40} \)

Hint:

Use Bayes' theorem when finding reverse probability: \(P(A|B)=\frac{P(B|A)P(A)}{P(B)}\).

Answer 1

The Correct Option is C