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The time needed for checking in at a motel is to be investigated. Historically, the process has had a standard deviation equal to 0.152. The means of 39 samples of n=20 are Click here for the Excel Data File a-1. Construct an

x chart for this process with three-sigma limits. (Do not round intermediate calculations. Round your answers to 2 decimal places.)

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Final answer:

The question pertains to constructing an x-chart for a motel check-in process where a historical standard deviation is provided, along with sample means. An x-chart includes the average of the sample means and the upper and lower control limits, which are calculated using three-sigma limits from the given standard deviation and sample size.

Step-by-step explanation:

The question involves constructing an x-chart for a motel check-in process with three-sigma limits, given a historical standard deviation for the process and the means of multiple samples. To create an x-chart with three-sigma limits, you typically use the average of the sample means (x-bar) and calculate the upper control limit (UCL) and lower control limit (LCL) using the formula:

  • UCL = x-bar + z*(σ/√n)
  • LCL = x-bar - z*(σ/√n)

Where z is the z-value corresponding to the desired confidence level (for three-sigma limits, z is typically 3), σ is the population standard deviation, and n is the sample size. Without the actual data from the Excel file, the specific values for UCL and LCL cannot be calculated. However, the understanding and approach to solving the problem have been described.

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