Question

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. $\frac{2}{7}$
• B. $\frac{3}{7}$
• C. $\frac{5}{7}$
• D. $\frac{5}{6}$

Answer 1

Answer: (C)

$\frac{5}{7}$

Answer 2

The correct answer is (C) : $\frac{5}{7}$
$\frac{^5C_2+^6C_2}{^2C_2+^3C_2+^4C_2+^5C_2+^6C_2}$
$=\frac{10+15}{1+3+6+10+15}=\frac{25}{35}$
$=\frac{5}{7}$