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| Question 933930:  11. An automobile battery manufacture offers an 18 month warranty on its car batteries. Under this warranty, if a battery fails within 18 months of purchase, the manufacturer replaces the battery at no charge to the consumer.  Assume that the lifetime of its car batteries is normally distributed with a mean of 32 months and a standard deviation of 7 months.
 
 A.	What percentage of batteries will be replaced free of charge?
 
 B.	If 200 batteries are sold in a given year each costing $150.00, then what was the total warranty costs of replacing defective batteries free ( Round up if necessary)
 
 
 Answer by stanbon(75887)
      (Show Source): 
You can put this solution on YOUR website! An automobile battery manufacture offers an 18 month warranty on its car batteries. Under this warranty, if a battery fails within 18 months of purchase, the manufacturer replaces the battery at no charge to the consumer. Assume that the lifetime of its car batteries is normally distributed with a mean of 32 months and a standard deviation of 7 months. 
 A. What percentage of batteries will be replaced free of charge?
 z(18) = (18-32)/7 = -2
 P(x < 18 months) = P(z < -2) = 0.02275 = 2.275% will fail in less than 18 months
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 B. If 200 batteries are sold in a given year each costing $150.00, then what was the total warranty costs of replacing defective batteries free ( Round up if necessary)
 Ans: 150*0.02275*200 = $682.50
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 Cheers,
 Stan H.
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