If the specification subgroup size is n = 4 and the known process parameters are μ = 2.75 and σ = .044,the control limits for the chart will be:
A) LCL = 2.684,UCL = 2.816.
B) LCL = 2.728,UCL = 2.772.
C) LCL = 2.618,UCL = 2.882.
D) LCL = 2.518,UCL = 2.998.

Question

If the specification subgroup size is n = 4 and the known process parameters are μ = 2.75 and σ = .044,the control limits for the  chart will be:
A) LCL = 2.684,UCL = 2.816. 
B) LCL = 2.728,UCL = 2.772. 
C) LCL = 2.618,UCL = 2.882. 
D) LCL = 2.518,UCL = 2.998.

Quizplus · Accepted Answer

For an 11eaae2c_ffa5_eea9_a6b1_c1247eed116c_TB3508_11 chart, the control limits can be calculated using the following formula:

UCL = μ + kσ/√n
LCL = μ - kσ/√n

Where k is the distance between the center line and the control limits in units of standard deviation, and is typically chosen based on the desired level of control.

For n = 4, k = 0.729 (based on a factor of d2 from the standard deviation table for subgroup size of 4). Substituting the given values, we get:

UCL = 2.75 + (0.729)(0.044)/√4 = 2.816
LCL = 2.75 - (0.729)(0.044)/√4 = 2.684

Therefore, the answer is choice A.

If the Specification Subgroup Size Is N = 4 and the Known