SCENARIO 18-3
a Quality Control Analyst for a Light Bulb

SCENARIO 18-3
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. $\begin{array}{ccc} \underline{\text { Day } }& \underline{\bar{X} \text { (in minutes) }} & \underline{\text {R}}\\1 & 58.5 & 5.1 \\2 & 47.6 & 7.8 \\3 & 64.3 & 6.1 \\4 & 60.6 & 5.7 \\5 & 63.7 & 6.2 \\6 & 57.5 & 6.0 \\7 & 55.0 & 5.4 \\8 & 54.9 & 6.1 \\9 & 55.0 & 5.9 \\10 & 62.7 & 5.0 \\11 & 61.9 & 7.1 \\12 & 60.0 & 6.5 \\13 & 58.3 & 5.9 \\14 & 52.0 & 5.2\end{array}$

-Referring to Scenario 18-3, suppose the sample mean and range data were based on 11 observations per day instead of 10. How would this change affect the lower and upper control
Limits of the R chart?

A) LCL would increase; UCL would decrease.
B) LCL would remain the same; UCL would decrease.
C) Both LCL and UCL would remain the same.
D) LCL would decrease; UCL would increase.