SCENARIO 19-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds)is too erratic and adversely affects expected profits.The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours.The sample mean and range for each hour are listed below.
She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds,respectively.
-Referring to Scenario 19-4,suppose the supervisor constructs an R chart to see if the variability in collection times is in-control.What is the center line of this R chart?
A)20.00
B)20.56
C)20.40
D)24.00

Question

SCENARIO 19-4
A factory supervisor is concerned that the time it takes workers to complete an important production task (measured in seconds)is too erratic and adversely affects expected profits.The supervisor proceeds by randomly sampling 5 individuals per hour for a period of 10 hours.The sample mean and range for each hour are listed below.
 She also decides that lower and upper specification limit for the critical-to-quality variable should be 10 and 30 seconds,respectively.
-Referring to Scenario 19-4,suppose the supervisor constructs an R chart to see if the variability in collection times is in-control.What is the center line of this R chart?
A)20.00 
B)20.56 
C)20.40 
D)24.00

Quizplus · Accepted Answer

The center line for an R chart is calculated as the average range (sum of ranges divided by number of samples). In this case, the sum of ranges is 216 and the number of samples is 50 (5 individuals sampled per hour for 10 hours), so the average range is 4.32. Therefore, the center line of the R chart is 20.40 (average sample range + lower specification limit = 10 + 10.40 = 20.40).

SCENARIO 19-4 A Factory Supervisor Is Concerned That the Time It Takes