प्र: 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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उत्तर : 2. "1/204"
व्याख्या :
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
समान प्रश्न
Since Nithya and Suganya exchange places, so Rita’s new position is the same as Monika’s earlier position. This position is 17th from the right and 10th from the left. Therefore Number of girls in the row = (16 + 1 + 9) = 26.