CHAPTER 14 Review Exercises 719 9. If the R chart and x chart both showed that the process of manufacturing aircraft altimeters is within statistical control, can we conclude that the altimeters satisfy the Federal Aviation Administration requirement of having errors of no more than 40 ft when tested at an altitude of 6000 ft? 10. Examine the following p chart for defective calculator batteries and briefly describe the action that should be taken. Review Exercises Energy Consumption. Exercises 1–4 refer to the amounts of energy consumed in the author’s home. (Most of the data are real, but some are fabricated.) Each value represents energy consumed (kWh) in a two-month period. Let each subgroup consist of the six amounts within the same year. Data are available for download at www.TriolaStats.com. Jan.–Feb. Mar.–April May–June July–Aug. Sept.–Oct. Nov.–Dec. Year 1 3637 2888 2359 3704 3432 2446 Year 2 4463 2482 2762 2288 2423 2483 Year 3 3375 2661 2073 2579 2858 2296 Year 4 2812 2433 2266 3128 3286 2749 Year 5 3427 578 3792 3348 2937 2774 Year 6 4016 3458 3395 4249 4003 3118 Year 7 5261 2946 3063 5081 2919 3360 Year 8 3853 3174 3370 4480 3710 3327 1. Energy Consumption: Notation After finding the values of the mean and range for each year, find the values of x and R. Then find the values of LCL and UCL for an R chart and find the values of LCL and UCL for an x chart. 2. Energy Consumption: R Chart Let each subgroup consist of the 6 values within a year. Construct an R chart and determine whether the process variation is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of statistically stable variation. 3. Energy Consumption: x Chart Let each subgroup consist of the 6 values within a year. Construct an x chart and determine whether the process mean is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of a statistically stable mean. 4. Energy Consumption: Run Chart Construct a run chart for the 48 values. Does there appear to be a pattern suggesting that the process is not within statistical control?
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