SOLUTION: A package of 12 recordable CDs contains 3 which are defective. If 4 CDs are selected at random, find the probability that: a. No defective CDs are found. b. 1 of the 4 CDs i

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Question 131112: A package of 12 recordable CDs contains 3 which are defective. If 4 CDs are selected at random, find the probability that:
a. No defective CDs are found.
b. 1 of the 4 CDs is defective.
c. 3 of the 4 CDs are defective.
Not a text book question. Thank you for your help :)
Answer by stanbon(57380) (Show Source):
You can put this solution on YOUR website!
A package of 12 recordable CDs contains 3 which are defective. If 4 CDs are selected at random, find the probability that:
a. No defective CDs are found.
b. 1 of the 4 CDs is defective.
c. 3 of the 4 CDs are defective.
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P(defective)= 3/12 = 1/4; P(non defective)=3/4
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a. P(No defective CDs are found)= (3/4)^4
b. P(1 of the 4 CDs is defective)= 4C1(1/4)(3/4)^3 = 0.421875...
c. P(3 of the 4 CDs are defective)=4C3(1/4)^3(3/4)= 0.421875...
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Cheers,
Stan H.