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a bag contains 4 red 3 black 2 white ballss if 3 balls are selected at random the probability of selecting at least one white ball is |
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Answer» Bag contains 4 red, 3 black and, 2 white balls Two balls are selected at random The total no. of ways of doing that is 10 C 2
= 8!×2! 10!
= 8!×2! 10×9×8!
= 2 10×9
=45 Now in the selection we need to ENSURE that at least on white ball is selected. Case 1 : 1 white ball + 1 ball of any other color This can be DONE in 2 C 1
×7 C 1
=2×7=14 ways Case 2 : 2 white ball This can be done in 2 C 2
=1 way ∴ probability of selecting atleast ONE white ball is = 45 14+1
= 45 15
= 3 1
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