Q: 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.
- 15/204false
- 21/204true
- 313/204false
- 4None of thesefalse
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Answer : 2. "1/204"
Explanation :
Answer: B) 1/204 Explanation: Let A, B, C be the events of getting a white ball in first, second and third draw respectively, then Required probability = PA∩B∩C = PA PBA PCA∩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 ∴PBA=317 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. ∴PCA∩B =216=18 Hence the required probability = 29×317×18=1204
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