TABLE 17-4
a Factory Supervisor Is Concerned That the Time

question 111

Multiple Choice

TABLE 17-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds) is too erratic and adversely affects expected profits. The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours. The sample mean and range for each hour are listed below.
$\begin{array}{ccc} \underline { \text {Hour } }& \underline { \bar { X } } & \underline { R }\\1 & 18.4 & 25 \\2 & 16.9 & 27 \\3 & 23.0 & 30 \\4 & 21.2 & 23 \\5 & 21.0 & 24 \\6 & 24.0 & 25 \\7 & 19.3 & 12 \\8 & 15.8 & 14 \\9 & 20.0 & 13 \\10 & 23.0 & 11\end{array}$

She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds, respectively.
-Referring to Table 17-4, suppose the supervisor constructs an $\bar { X }$ chart to see if the process is in-control. What is the center line of the chart?

• A) 20.00
• B) 20.26
• C) 21.00
• D) 24.26

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Definitions:

Interquartile Range

A measure of statistical dispersion, representing the difference between the 75th and 25th percentiles, or the middle 50% of a data set.

Outliers

Data points that lie far outside the range of the majority of a data set, deviating significantly from other observations.

Interquartile Range

The difference between the 25th and 75th percentile in a data set, showing the spread of the middle half of the values.

Scores

Values or measurements obtained from assessments, tests, or evaluations.