a)What is the minimum tolerable tear resistance, ie two standard deviations below the mean? Enter the correct number of significant figures. b)What is the maximum tolerable tear resistance, ie two standard deviations above the mean? Enter the correct number of significant figures.
Your company manufactures plastic wrap for food storage. The tear resistance of the wrap, denoted by X, must be controlled so that the wrap can be torn off the roll without too much effort but it does not tear too easily when in use.
In a series of tests (see data table below), 15 rolls of wrap are made under carefully controlled conditions and the tear resistance of each roll is measured. The results are used as the basis of a quality assurance specification. If X for a subsequently produced roll falls more than two standard deviations away from the test period average, the process is declared out of specification and production is suspended for routine maintenance.
| Roll | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| X | 134 | 131 | 129 | 133 | 135 | 131 | 134 | 130 | 131 | 136 | 129 | 130 | 133 | 130 | 133 |
Write an Excel spreadsheet to calculate the sample mean and sample standard deviations.
The
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a)What is the minimum tolerable tear resistance, ie two standard deviations below the mean? Enter the correct number of significant figures.
b)What is the maximum tolerable tear resistance, ie two standard deviations above the mean? Enter the correct number of significant figures.
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