Question 399983
there are 8 green,10 red and 12 yellow balls. If we pick a ball at random what is the probability that ball is not green and red.
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Did you mean "not green AND red" or 
did you mean to say not green OR red.
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The prob of the former is zero because no ball is green AND red.
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The prob of latter is 1-(12/30) = 1-(2/5) = 3/5
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Cheers,
Stan H.