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 Question from Ruby, a student: We are admiring hand blown glass ornaments 5% are unmarketable due to defects what is the probability the 3rd ornament is the first defective one

Hi Ruby,

I think you are expected to assume that the process of admiring the ornaments is a Bernoulli process, the important part here is that the probability that an ornament has a defect is 5%, regardless of the state of any ornaments you have examined previously.

For the third ornament you examine to be the first defective on you discover both the first and second ornaments must not have defects. The probability that the first ornament you examine has no defects is 95% or 0.95. What is the probability that the second ornament you examine has no defect? What is the probability that the first ornament you examine has no defect AND the second ornament you examine has no defect? What is the probability that the first ornament you examine has no defect AND the second ornament you examine has no defect AND the third ornament you examine is defective?

Penny

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