Suppose a Large Labor Union Wishes to Estimate the Mean $\bar { x } = 7.5$

question 80

Multiple Choice

Suppose a large labor union wishes to estimate the mean number of hours per month a union member is absent from work. The union decides to sample 348 of its members at random and monitor the working time of each of them for 1 month. At the end of the month, the total number of hours absent from work is recorded for each employee. If the mean and standard deviation of the sample are $\bar { x } = 7.5$ hours and $s = 3.5$ hours, find a $99 \%$ confidence interval for the true mean number of hours a union member is absent per month. Round to the nearest thousandth.

• A) \(7.5 \pm .258\)
• B) \(7.5 \pm .026\)
• C) \(7.5 \pm .483\)
• D) \(7.5 \pm .186\)

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Definitions:

Single Phase Loads

Electrical loads operating with a single phase power supply, characterized by the use of two wires: one power wire and one neutral wire.

Three Wire Wye

A three-phase power configuration where three branches in a circuit are connected at a common point, resembling the letter Y.

High Leg

In electrical systems, a term referring to a conductor in a delta connection that has a higher voltage with respect to ground than the other two conductors.

Open Delta

A transformer connection method using two transformers to form a delta configuration, typically used when one transformer of a three-phase system is out of service or for economy in a lightly loaded system.