3. The following table gives the average and range in kilograms for tensile test

Question

3. The following table gives the average and range in kilograms for tensile tests on an improved plastic cord. The subgroup size is 4. Determine the trial cen- tral line and control limits. If any points are out of control, assume assignable causes and calculate revised limits and central line. SUBGROUP NUMBER 14 15 16 17 18 19 20 21 SUBGROUP NUMBER X 32 24 32 26 24 24 28 23 24 26 482 506 496 478 484 506 476 485 490 463 469 474 476 23 23 466 484 466 470 494 486 496 488 482 25 498 464 24 484 4 24 23 25 29 25 23 24 25 10 27 24 12 13 245 CONTROL CHARTS FOR VARIABLES

Explanation / Answer

Here xbar-bar is the average of all mean.

xbar-bar = 482.52

Rbar = 25.04

Subgroup size = 4

Central line = xbar -bar = 482.52

Lower control limit = Process mean - A2 R = 482.52 - 0.729 * 25.04 = 464.266

Upper control Limit = Process mean + A2 R = 482.52 + 0.729 * 25.04 = 500.744

UCLR = D4 Rbar = 2.282 * 25.04 = 57.14

LCLR = D3 Rbar  = 0

Here there are subgroup number 12, 15 ,19 and 23 are out of control limits.

Here we will exclude these value and calculate the new revised limits.

xbar-bar = 482.095

Rbar = 25.43

Subgroup size = 4

Central line = xbar -bar = 482.095

Lower control limit = Process mean - A2 R = 482.095 - 0.729 * 25.43 = 463.56

Upper control Limit = Process mean + A2 R = 482.095 + 0.729 * 25.43 = 500.63

UCLR = D4 Rbar = 2.282 * 25.04 = 57.14

LCLR = D3 Rbar  = 0

Now, there is no process is out of control limt

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.