SOLUTION: The length of steel rods cut by a machine is normally distributed with mean 13.8 cm. It is found that 1.5% of all rods are less than 13.2 cm long. Find the standard deviation of ro

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Question 280800: The length of steel rods cut by a machine is normally distributed with mean 13.8 cm. It is found that 1.5% of all rods are less than 13.2 cm long. Find the standard deviation of rod lengths produced by this machine.
Answer by stanbon(75887) About Me  (Show Source):
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The length of steel rods cut by a machine is normally distributed with mean 13.8 cm. It is found that 1.5% of all rods are less than 13.2 cm long. Find the standard deviation of rod lengths produced by this machine.
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Find the z-score with left tail = 0.015
invNorm(0.015) = -2.1701
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Use the form: x = zs+u to find "s":
13.2 = -2.1701s + 13.8
-2.1701s = -0.6
s = standard deviation = 0.2765
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Cheers,
Stan H.