A factory produces supporting devices for semiconductor manufacturing. Nine samples of the devices are selected and their lengths (millimetre) are recorded as follows: 1.03mm 0.99 mm 0.98 mm 1.01 mm...

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Extracted text: A factory produces supporting devices for semiconductor manufacturing. Nine samples of the devices are selected and their lengths (millimetre) are recorded as follows: 1.03mm 0.99 mm 0.98 mm 1.01 mm 1.01 mm 0.97 mm 1.04 mm 1.03 mm 0.99 mm Compute a 99% confidence interval for the mean length of the devices by assuming that the distribution is approximately normal.