Question 724254
If a box contains 10 left handed and 20 right handed screws what is the probability of obtaining at least one right handed screw in drawing 2 screws with replacement? 
P(at least 1 right) = 1 - P(2 left) = 1 - (1/3)^2 = 8/9
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Will the probability in the answer in the first question increase or decrease if we draw without replacement.
Ans: increase
1 - (10/30)(9/29) = 0.8966
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Cheers,
Stan H.