JEE Mains · Maths · STD 12 - 13. probability
Three urns \(A\), \(B\) and \(C\) contain \(7\) red, \(5\) black; \(5\) red, \(7\) black and \(6\) red, \(6\) black balls, respectively. One of the urn is selected at random and a ball is drawn from it. If the ball drawn is black, then the probability that it is drawn from urn \(\mathrm{A}\) is :
- A \(\frac{4}{17}\)
- B \(\frac{5}{18}\)
- C \(\frac{7}{18}\)
- D \(\frac{5}{16}\)
Answer & Solution
Correct Answer
(B) \(\frac{5}{18}\)
Step-by-step Solution
Detailed explanation
\(A\ \ \ \ \ B \ \ \ \ \ C \) \(7 \mathrm{R}, 5 \mathrm{~B}\ \ \ \ 5 \mathrm{R}, 7 \mathrm{~B} \ \ \ \ 6 \mathrm{R}, 6 \mathrm{~B}\) \( \mathrm{P}(\mathrm{B})=\frac{1}{3} \cdot \frac{5}{12}+\frac{1}{3} \cdot \frac{7}{12}+\frac{1}{3} \cdot \frac{6}{12} \)…
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