Statistics for Business: Decision Making and Analysis, 3rd Edition

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1. 33. Shafts

   1. By the Empirical Rule, 0.025; 0.02275 from the normal table.

   2. 0.95⁸⁰ = 0.0165.0.9973⁸⁰ = 0.8055.

   3. Yes

   4. No

   5. Narrower control limits make one more likely to conclude out of control (and hence a increase the chance of a Type I error).

   6. K₃ = − 0.18 and K₄ = 0.15. Five days is enough since n is larger than 10 times the square of K₃ or {K₄}.

2. 35. Insulator

   1. Using the first 5 days, the mean is about 449.88 with s = 1.14. The skewness during this period is K₃ = − 0.45 and K₄ = 0.81. Twelve per day is just enough to meet the CLT condition.

   2. The process is out of control in both.

   3. The variation increases beyond that specified in the design. This variation also allows the mean to go out of control.

3. 37. 4M ANALYTICS: Monitoring an Email ...