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TS EAMCET · Maths · Probability

In an entrance test there are multiple choice questions. There are four possible answers to each question, of which one is correct. The probability that a student know the answer to a question is \(9 / 10\). If he gets the correct answer to a question, then the probability that he was guessing is

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

Answer & Solution

Correct Answer

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

Step-by-step Solution

Detailed explanation

Let \(E_1\) : The event that the students knows the answer and \(E_2\) : The event that the student guesses the answer \(\therefore \quad P\left(E_1\right)=\frac{9}{10} \quad\) and \(\quad P\left(E_2\right)=1-\frac{9}{10}=\frac{1}{10}\) Let \(E\) : The answer is correct. The…