SOLUTION: a battery has a mean life of 320 hours and a standard deviation of 20 hours and by assuming that this distribution is normal, estimate the probability that the battery will last fo
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-> SOLUTION: a battery has a mean life of 320 hours and a standard deviation of 20 hours and by assuming that this distribution is normal, estimate the probability that the battery will last fo
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Question 1100900: a battery has a mean life of 320 hours and a standard deviation of 20 hours and by assuming that this distribution is normal, estimate the probability that the battery will last for more than 380 hours. Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website! Probability(P) ( X > 380 ) = 1 - P( X < 380 )
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z-value = (380 - 320) / 20 = 3
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find in z-tables the probability associated with the z-value of 3
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P( X < 380 ) = 0.9987
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P( X > 380 ) = 1 - 0.9987 = 0.0013
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