Instruction 18-9 A Quality Control Analyst for a Light Bulb Manufacturer Is

Multiple Choice

Instruction 18-9
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 Instruction 18-9,suppose the analyst constructs an R chart to see if the variability in production times is in control.The R chart is characterised by which of the following?

A) Increasing trend.
B) In control.
C) Decreasing trend.
D) Points outside the control limits.