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 (1) $\frac{5}{3}$ (2) $\frac{2}{7}$ (3) $\frac{3}{7}$ (4) $\frac{5}{6}$
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\\
(1) $\frac{5}{3}$\\
(2) $\frac{2}{7}$\\
(3) $\frac{3}{7}$\\
(4) $\frac{5}{6}$