SOLUTION: The length of life for an automatic dishwasher is approximately normally distributed, with a mean of 4.5 years and a S.D. of 2 years. If this type of dishwasher is guaranteed for 1

Question 1012752: The length of life for an automatic dishwasher is approximately normally distributed, with a mean of 4.5 years and a S.D. of 2 years. If this type of dishwasher is guaranteed for 18 months, what fraction of the sales will require replacement?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The length of life for an automatic dishwasher is approximately normally distributed, with a mean of 4.5 years and a S.D. of 2 years. If this type of dishwasher is guaranteed for 18 months, what fraction of the sales will require replacement?
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4.5 yrs = 4.5*12 = 50 monts
z(18) = (18-50)/24 = -1.33
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P(last less than 18 mths) = P(z < -1.33) = 9.18%
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Cheers,
Stan H.
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