SCENARIO 15-3
a Quality Control Analyst for a Light Bulb

question 9

Multiple Choice

SCENARIO 15-3
A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic.Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.
$\begin{array}{rcr}\text { Day }& \bar{X} \text { (inminutes) } &R\\1 & 58.5 & 5.1 \\2 & 47.6 & 7.8 \\3 & 64.3 & 6.1 \\4 & 60.6 & 5.7 \\5 & 63.7 & 6.2 \\6 & 57.5 & 6.0 \\7 & 55.0 & 5.4 \\8 & 54.9 & 6.1 \\9 & 55.0 & 5.9 \\10 & 62.7 & 5.0 \\11 & 61.9 & 7.1 \\12 & 60.0 & 6.5 \\13 & 58.3 & 5.9 \\14 & 52.0 & 5.2\end{array}$
-Referring to SCENARIO 15-3, suppose the analyst constructs an X chart to see if the production process is in-control.What is the lower control limit (LCL) for this chart?

• A)47.60
• B)56.15
• C)57.15
• D)58.05

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Definitions:

Chi-Squared Curve

A graphical representation of the chi-squared distribution, showing the probability of chi-squared values along the x-axis.

Degrees of Freedom

A statistical concept that defines the number of independent pieces of information in a dataset used in parameter estimates.

Population Variances

The measurement of how much the numbers in a specific population are spread out from their mean.

Test Statistic

A value calculated from sample data that is used in hypothesis testing to determine whether to reject the null hypothesis.