Problem 10-12

The time needed for checking in at a hotel is to be investigated. Historically, the process has had a standard deviation equal to .146. The means of 39 samples of n = 21 are

Sample	Mean	Sample	Mean	Sample	Mean	Sample	Mean
1	3.86	11	3.88	21	3.84	31	3.88
2	3.90	12	3.86	22	3.82	32	3.76
3	3.83	13	3.88	23	3.89	33	3.83
4	3.81	14	3.81	24	3.86	34	3.77
5	3.84	15	3.83	25	3.88	35	3.86
6	3.83	16	3.86	26	3.90	36	3.80
7	3.87	17	3.82	27	3.81	37	3.84
8	3.88	18	3.86	28	3.86	38	3.79
9	3.84	19	3.84	29	3.98	39	3.85
10	3.80	20	3.87	30	3.96

a-1.	Construct an xx -chart for this process with three-sigma limits. (Do not round intermediate calculations. Round your answers to 2 decimal places.)

UCL
LCL

a-2.	Is the process in control?
	Yes No

b.	Analyze the data using a median run test and an up/down run test. What can you conclude?

Test	Conclusion
Median	(Click to select) Random Non-random
Up/Down	(Click to select) Random Non-random