# Question

A random sample of n= 40 pipe sections resulted in a mean wall thickness of 0.1264 in. and a standard deviation of 0.0003 in. We assume that wall thickness is normally distributed.

(a) Between what limits can we say with 95% confidence that 95% of the wall thicknesses should fall?

(b) Construct a 95% confidence interval on the true mean thickness. Explain the difference between this interval and the one constructed in part (a).

(a) Between what limits can we say with 95% confidence that 95% of the wall thicknesses should fall?

(b) Construct a 95% confidence interval on the true mean thickness. Explain the difference between this interval and the one constructed in part (a).

## Answer to relevant Questions

Estimate process capability using the x and R charts for the power supply voltage data in Exercise 6.8 (note that early printings of the 7th edition indicate Exercise 6.2). If specifications are at 350 ± 50 V, calculate Cp, ...A process is in statistical control with x = 39.7 and R = 2.5. The control chart uses a sample size of n= 2. Specifications are at 40 ± 5. The quality characteristic is normally distributed. USL = 40 + 5 = 45; LSL = 40 – ...Consider the “minute clinic” waiting time data in Exercise 6.66. These data may not be normally distributed. Set up a CUSUM chart for monitoring this process. Does the process seem to be in statistical ...Consider the viscosity data in Exercise 9.9. Suppose that the target value of viscosity is µ0 = 3,150 and that it is only important to detect disturbances in the process that result in increased viscosity. Set up and apply ...Reconstruct the control chart in Exercise 9.29 using = 0.4 and L = 3. Compare this chart to the one constructed in 9.29 12.16 , CL = 0 = 950, UCL = 968.24, LCL = 931.76.Post your question

0