SOLVED

31) Ten samples of a process measuring the number of returns per 100 receipts were taken for a local retail store. The number of returns were 10, 9, 11, 7, 3, 12, 8, 4, 6, and 11. Find the standard deviation of the sampling distribution for the p-bar chart. A) There is not enough information to answer the question. B) .081 C) 8.1 D) .0273 E) .0863 32) An x-bar control chart was examined and no data points fell outside of the limits. Can this process be considered in control? A) Not yet, there could be a pattern to the points. B) Not yet, the R-chart must be checked. C) Not yet, the number of samples must be known. D) Yes. E) Both A and B 33) Statistical process control charts: A) display the measurements on every item being produced. B) display upper and lower limits for process variables or attributes and signal when a process is no longer in control. C) indicate to the process operator the average outgoing quality of each lot. D) indicate to the operator the true quality of material leaving the process. E) are a graphic way of classifying problems by their level of importance, often referred to as the 80-20 rule. 34) The Central Limit Theorem: A) is the theoretical foundation of the c-chart. B) states that the average of assignable variations is zero. C) allows managers to use the normal distribution as the basis for building some control charts. D) states that the average range can be used as a proxy for the standard deviation. E) controls the steepness of an operating characteristic curve. 35) For a 3-sigma x-bar chart where the process standard deviation is known, the upper control limit: A) is 3σ below the mean of sample means for a 3σ control chart. B) is 3σ above the mean of sample means for a 3σ control chart. C) is 3σ/ below the mean of sample means for a 3σ control chart. D) is 3σ/ above the mean of sample means for a 3σ control chart. E) cannot be calculated unless the average range is known. 36) Up to three standard deviations above or below the centerline is the amount of variation that statistical process control allows for: A) Type I errors. B) about 95.5% variation. C) natural variation. D) all types of variation. E) assignable variation. 37) A manager wants to build 3-sigma x-bar control limits for a process. The target value for the mean of the process is 10 units, and the standard deviation of the process is 6. If samples of size 9 are to be taken, what will be the upper and lower control limits, respectively? A) -8 and 28 B) 16 and 4 C) 12 and 8 D) 4 and 16 E) 8 and 12 38) Jars of pickles are sampled and weighed. Sample measures are plotted on control charts. The ideal weight should be precisely 11 oz. Which type of chart(s) would you recommend? A) p-chart B) c-chart C) both an x-bar chart and an R-chart D) an x-bar chart, but not an R-chart E) both a p-chart and a c-chart 39) If = 23 ounces, σ = 0.4 ounces, and n = 16, what will be the ±3σ control limits for the x-bar chart? A) 21.8 to 24.2 ounces B) 23 ounces C) 22.70 to 23.30 ounces D) 22.25 to 23.75 ounces E) 22.90 to 23.10 ounces 40) The usual purpose of an R-chart is to signal whether there has been a: A) gain or loss in dispersion. B) change in the percent defective in a sample. C) change in the central tendency of the process output. D) change in the number of defects in a sample. E) change in the consumer’s risk.