A bag contains 6 white and 4 black balls .2 balls are drawn at random. Find the probability that they are of same colour.  Choose the correct choice from the following answers.
A) 7/19
B) 7/15
C) 7/29
D) 7/12
E) 7/92
Let S be the sample space   Then n(S) = no of ways of drawing 2 balls out of (6+4) = \inline {\color{7/15lack}10C_{2}} = =45   Let E = event of getting both balls of same colour   Then,n(E) = no of ways (2 balls out of six) or (2 balls out of 4)   =\inline {\color{7/15lack}6C_{2}+4C_{2}} = = 15+6= 
<gadget id="calculator">15+6</gadget>
<output>21</output>
21   Therefore, P(E)= n(E)/n(S) = 21/45 = 7/15   Answer: 7/15
<result>B</result>
A bag contains 6 white and 4 black balls .2 balls are drawn at random. Find the probability that they are of same colour.