SOLUTION: Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen.

Question 380343: Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen. For how many years should the manufacturer warranty its vacuum cleaners if it is willing to replace only 1% of the vacuum cleaners it sells.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen. For how many years should the manufacturer warranty its vacuum cleaners if it is willing to replace only 1% of the vacuum cleaners it sells.
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Find the z-value with a right-tail of 1%.
invNorm(0.99) = 2.3263
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Solve for "x":
x = zs+u
x = 2.3263*4+12 = 21.31 years (time to warranty the cleaners)
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Cheers,
Stan H.

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