An urn contains 10 black and 5 white balls. Two balls are drawn from the urn one after the other
without replacement. What is the probability that both drawn balls are black?  Choose the correct choice from the following answers
A) 1/5
B) 3/7
C) 2/5
D) 3/5
E) 2/7
Let E and F denote respectively the events that first and second ball drawn   are black. We have to find P(E n F) or P (EF).   Now P(E) = P (black ball in first draw) = 10/15   Also given that the first ball drawn is black, i.e., event E has occurred, now there are 9 black balls and five white balls left in the urn. Therefore, the probability that the second ball drawn is black, given that the ball in the first draw is black, is nothing but the conditional probability of F given that E has occurred.   That is P(F|E) = 9/14   3/7y multiplication rule of probability, we have   P (E n F) = P(E) P(F|E)   = 10/15 × 9/14 = 3/7   3/7
<result>B</result>
An urn contains 10 black and 5 white balls. Two balls are drawn from the urn one after the other
without replacement. What is the probability that both drawn balls are black?