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Re: A manufacturer is using glass as the surface [#permalink]
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fozzzy wrote:
could you please explain why the power is raised to 10. is it because 10 phone so raise by 10 or any other explanation?


The probability that a phone will pass the test is 0.95, thus the probability that all 10 phones will pass the test is P(all 10 phones pass test)=0.95^10.
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Re: A manufacturer is using glass as the surface [#permalink]
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probability for one phone passing the test = 0.95
probability for 10 phones passing the test = 0.95 AND 0.95 AND 0.95 ..... = 0.95 * 0.95 * 0.95 .... = 0.95^10
probability for at least one phone not passing the test = 1 - 0.95^10

Answer: C
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Re: A manufacturer is using glass as the surface [#permalink]
In this case, as written above, it is much easier to calculate the probability that none of the phones will be defect and erase that from 100%.

Probability of passing 1 phone = 0.95.
Probability of passing 10 phones = 0.95*0.95*...*0.95 = 0.95^10
Probability of not passing 10 phones = 1-0.95^10

Answer choice: C
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Re: A manufacturer is using glass as the surface [#permalink]
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Re: A manufacturer is using glass as the surface [#permalink]
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