SOLUTION: The lifetime of ZZZ batteries is normally distributed with a mean of 270 hours and a standard deviation of 10 hours. What number of hours would represent the 40th percentile in thi

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Question 479673: The lifetime of ZZZ batteries is normally distributed with a mean of 270 hours and a standard deviation of 10 hours. What number of hours would represent the 40th percentile in this distribution? Please help me with this I do t understand it & how to show my work. Thank you.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The lifetime of ZZZ batteries is normally distributed with a mean of 270 hours and a standard deviation of 10 hours. What number of hours would represent the 40th percentile in this distribution?
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Find the z-value with a left-tail of 40%
invNorm(0.40) = -0.2533
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find the correspondign hour value using x = zs+u
x = -0.2533*10+ 270 = 267.47 hrs.
Round up to 267 hrs
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Cheers,
Stan H.
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