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TS EAMCET · Maths · Probability

\(A\) and \(B\) are the two groups of books. Group \(A\) consists of 8 science and 5 engineering books and the group \(B\) consists of 6 science and 7 engineering books. When an unbiased die is rolled, if 2 or 5 turns up, a book is selected at random from the group \(A\). Otherwise a book is selected at random from the \(B\) group. When an unbiased die is rolled, the probability of selecting a science book is

  1. A \(\frac{13}{24}\)
  2. B \(\frac{34}{35}\)
  3. C \(\frac{20}{39}\)
  4. D \(\frac{13}{36}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{20}{39}\)

Step-by-step Solution

Detailed explanation

Let \(E=\) Science book selected If 2 or 5 turns up after thrown a dice, then select a subject from \(A\) otherwise from \(B\). \( \therefore P(E)=\frac{2}{6} \times \frac{8}{13}+\frac{4}{6} \times \frac{6}{13}=\frac{40}{78}=\frac{20}{39} \)