Question 1102356: A manufacturer knows that their items have a normally distributed lifespan, with a mean of 4.3 years, and standard deviation of 1.2 years.
If 22 items are picked at random, 6% of the time their mean lifespan will be less than how many years?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A manufacturer knows that their items have a normally distributed lifespan, with a mean of 4.3 years, and standard deviation of 1.2 years.
If 22 items are picked at random, 6% of the time their mean lifespan will be less than how many years?
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mean of the sample means:: 4.3
std of the sample means:: 1.2/sqrt(22) = 0.2558
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Find the z-value with a left tail of 6%
invNorm(0.06) = -1.5548
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Find the corresponding lifespan::
x = -1.5548*0.2558 + 4.3
x = 3.9
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Cheers,
Stan H.
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