A bag contains 12 white and 18 black balls. 2balls are drawn in succession. What is the probability that first is white and second is black?  Choose the correct choice from the following answers:
A) 31/145
B) 23/145
C) 36/145
D) 31/115
E) 41/215
The probability that first ball is white:   =12C130C1=12C130C1   =1230=1230   =25=25   Since, the ball is not replaced; hence the number of balls left in bag is 29.   Hence, the probability the second ball is black:   =18C129C1=18C129C1   =1829=1829   Required probability,   =(25)×(1829)=(25)×(1829)   =36/145   23/145
<result>B</result>
A bag contains 12 white and 18 black balls. 2balls are drawn in succession. What is the probability that first is white and second is black?