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 Posted: Mon Aug 27, 2007 9:54 pm Post subject: probability Q-1 |
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help me to solve these probability questions
1.In a bag of balloons, the ratio of red balloons to other colours is 1:5, if 3 balloons are selected from the bag at random, what is the probability that (a) at least one balloon is red, (b) exactly one balloon is red.?
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ratindasgupta
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| Posted: Mon Aug 27, 2007 11:53 pm Post subject: |
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Assume that 1 balloon is red and there are 5 balloons of other colours.
Atleast 1 red = 1 - (no red)
No red = 5/6 x 4/5 x 3/4 = 1/2
Atleast 1 red = 1- 1/2 = 1/2
Exactly 1 red = (1C1 x 5C2)/6C3 = 1/2
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