An urn contains 4 white 6 black and 8 red balls . If 3 balls are drawn one by one without replacement, find the probability of getting all white balls.

Let A, B, C be the events of getting a white ball in first, second and third draw respectively, then 

 Required probability =  P A ? B ? C 

=  P A P B A P C A ? B

 Now, P(A) = Probability of drawing a white ball in first draw = 4/18 = 2/9

When  a white ball is drawn in the first draw there are 17 balls left in the urn, out of which 3 are white

  ? P B A = 3 17 

Since the ball drawn is not replaced, therefore after drawing a white ball in the second draw there are 16 balls left in the urn, out of which 2 are white.

  ? P C A ? B = 2 16 = 1 8

 Hence the required probability =  2 9 × 3 17 × 1 8 = 1 204