# Question: Control chart x and s for are maintained on a

Control chart x and s for are maintained on a process. After 25 preliminary subgroups each of size 3 are evaluated, you have the following data:

(a) Set up control charts using these data.

(b) Assume that the process exhibits statistical control. Estimate the process mean and standard deviation.

(c) Suppose that the quality characteristic is normally distributed with specifications at 2.25 + – 4. Estimate the fraction nonconforming produced by this process.

(d) How much reduction in process variability would be required to make this a Six Sigma process?

The Motorola Six Sigma concept is to reduce the variability in the process so that the specification limits are at least six standard deviations from the mean (text p. 29). If the process mean was centered at the specification midpoint, this would require a standard deviation of

(a) Set up control charts using these data.

(b) Assume that the process exhibits statistical control. Estimate the process mean and standard deviation.

(c) Suppose that the quality characteristic is normally distributed with specifications at 2.25 + – 4. Estimate the fraction nonconforming produced by this process.

(d) How much reduction in process variability would be required to make this a Six Sigma process?

The Motorola Six Sigma concept is to reduce the variability in the process so that the specification limits are at least six standard deviations from the mean (text p. 29). If the process mean was centered at the specification midpoint, this would require a standard deviation of

**View Solution:**## Answer to relevant Questions

Reconsider the situation described in Exercise 6.1. Suppose that several of the preliminary 20 samples plot out of control on the R chart. Does this have any impact on the reliability of the control limits on the x chart? A TiW layer is deposited on a substrate using a sputtering tool. Table 6E.14 contains layer thickness measurements (in angstroms) on 20 subgroups of four substrates. (a) Setup x and R control charts on this process. Is the ...The data in Table 6E.17 were collected form a process manufacturing power supplies. The variable of interest is output voltage, and n = 5. (a) Compute center lines and control limits suitable for controlling future ...An chart with three-sigma limits has parameters as follows: UCL = 104 Center line = 100 LCL = 96 n = 5 Suppose the process quality characteristic being controlled is normally distributed with a true mean of 98 and a ...Consider the chart in Exercise 6.55. Find the average run length for the chart.Post your question