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

question 192

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.
$\begin{array}{ccc}\underline{\text { Day }}&\underline{ \bar{X} \text { (inminutes) }}& \underline{\text { R}}\\1 & 58.5 & 5.1 \\2 & 47.6 & 7.8 \\3 & 64.3 & 6.1 \\4 & 60.6 & 5.7 \\5 & 63.7 & 6.2 \\6 & 57.5 & 6.0 \\7 & 55.0 & 5.4 \\8 & 54.9 & 6.1 \\9 & 55.0 & 5.9 \\10 & 62.7 & 5.0 \\11 & 61.9 & 7.1 \\12 & 60.0 & 6.5 \\13 & 58.3 & 5.9 \\14 & 52.0 & 5.2\end{array}$
-Referring to SCENARIO 15-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control.What is the upper control limit for this R chart?

• A)10.66
• B)9.37
• C)7.98
• D)6.34

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Definitions:

Positively Skewed

A distribution of data where most values are concentrated on the left side, with a long tail extending to the right.

Standard Error

A statistic that measures the dispersion of sample means around the population mean.

Sample Mean

The arithmetic average of a sample set of data, used to estimate the population mean.

Normally Distributed

Describes a data set that follows a bell-shaped curve where most observations cluster around the mean and probabilities for values taper off symmetrically towards both extremes.