JEE Mains · Maths · STD 12 - 13. probability
A bag contains \(6\) balls. Two balls are drawn from it at random and both are found to be black. The probability that the bag contains at least \(5\) black balls is
- A \(\frac{5}{7}\)
- B \(\frac{2}{7}\)
- C \(\frac{3}{7}\)
- D \(\frac{5}{6}\)
Answer & Solution
Correct Answer
(A) \(\frac{5}{7}\)
Step-by-step Solution
Detailed explanation
\(\frac{{ }^5 C _2+{ }^6 C _2}{{ }^2 C _2+{ }^3 C _2+{ }^4 C _2+{ }^5 C _2+{ }^8 C _2}=\frac{10+15}{1+3+6+10+15}\) \(=\frac{25}{35}=\frac{5}{7}\)
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