CH 6 Supplement and CH 8 Problems Problem #1 Checkout time at a supermarket is monitored using a mean (x-bar) and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges (in minutes) were computed as follows: Sample Mean Range 1 3.06 0.42 2 3.15 0.50 3 3.11 0.41 4 3.13 0.46 5 3.06 0.46 6 3.09 0.45 Determine the 3-sigma upper and lower limits for mean (x-bar) and range charts. Is the process in control? Explain. Problem #2 Given the following data for the number of defects per spool of cable, using 3-sigma limits, is the process in control? Observations 1 Number of defects 2 3 2 3 1 4 5 0 6 1 3 7 2 8 9 10 11 12 13 0 2 1 3 1 2 14 0 Problem #3 Given the following list of machines, the standard deviation for each, and specifications for a job that may be processed on that machine, determine which machine(s) are capable of performing the given jobs. Machine Standard Deviation (in.) Job Specification (+/- in.) 001 0.02 0.05 002 0.04 0.07 003 0.10 0.18 004 0.05 0.15 005 0.01 0.04 Problem #4 A car radio supplier is going to open a new plant., and is trying to decide on whether to locate in Dallas or Detroit. Given the following costs: Dallas Detroit Fixed costs $600,000 $800,000 Variable costs $28/radio $22/radio a) Perform an analysis of the volume over which each location is preferable. b) How does your answer change if Dallas's fixed costs increase by 10%