SOLUTION: A shipment of 12 stereos contains six defective units. Four of the units are shipped to a retail store. What is the probability that at least two units are good?

Question 1069535: A shipment of 12 stereos contains six defective units. Four of the units are shipped to a retail store.
What is the probability that at least two units are good?
Found 2 solutions by Boreal, Fombitz:
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
It is 1- probability 1 unit is good or 0 units are good.
p=(1/2)
four defective is (6/12)(5/11)(4/10)(3/9)=360/11880=0.0303
three defective is 4(6/12)(5/11)(4/10)(6/9)=2880/11880=0.2424
That is 0.2727
probability at least two are good is 1-0.2727=0.7273 ANSWER
(probability two defective is (6/12)(5/11(6/10)(5/9)*6=5400/11880=0.4545)

Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
So there are 16 possible outcomes.
1 has 4 Good stereos
4 have 3 Good stereos
6 have 2 Good stereos
4 have 1 Good stereo
1 has 0 Good stereos
So there are 11 that have at least 2 Good stereos.

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