The Watson Electric Company produces incandescent lightbulbs. The following data on the number of lumens for 40-watt lightbulbs were collected when the process was in control.

a. Calculate control limits for an R-chart and an X̅-chart.

b. Since these data were collected, some new employees were hired. A new sample obtained the following readings: 625, 592, 612, and 635. Is the process still in control?

Transcribed Image Text:

Sample 1 604 597 581 620 590 1 2 3 4 5 OBSERVATION 2 612 601 570 605 614 3 588 607 585 595 608 4 600 603 592 588 604