TABLE 17-3
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.

-Referring to Table 17-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the lower control limit for this R chart?
A) 4.84
B) 3.37
C) 2.98
D) 1.34

Question

TABLE 17-3
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.
 
-Referring to Table 17-3, suppose the analyst constructs an R chart to see if the variability in production times is in-control. What is the lower control limit for this R chart?
A) 4.84 
B) 3.37 
C) 2.98 
D) 1.34

Quizplus · Accepted Answer

The lower control limit (LCL) for an R chart is calculated using the formula LCL = D3 * R-bar, where D3 is a constant that depends on the sample size. Given the options, 1.34 is the most plausible LCL value.

TABLE 17-3 A Quality Control Analyst for a Light Bulb Manufacturer Is