SOLUTION: An unscrupulous manufacturerknows that in a box of a dozen light bulbs,which he intends selling to a customer.four are in fact not working.He watches nervously as the customer insi

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Question 261681: An unscrupulous manufacturerknows that in a box of a dozen light bulbs,which he intends selling to a customer.four are in fact not working.He watches nervously as the customer insists on removing three and testing them.What is the probability that only one of the three tested fails to work?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
An unscrupulous manufacturer knows that in a box of a dozen light bulbs,which he intends selling to a customer.four are in fact not working.
He watches nervously as the customer insists on removing three and testing them.
What is the probability that only one of the three tested fails to work?
P(pick a bad bulb) = 4/12 = 1/3
P(1 in three is bad) = 3C1(1/3)(2/3)^2 = 3*(1/3)(2/3)^2 = 4/9
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Cheers,
Stan H.