4.41. Which of the following is a measure of dispersion? a. Median b. Mode c. Average d. Interquartile range 4.42. The random selection of a sample: a. Theoretically means that each item has an equal chance to be selected b. Ensures that the sample average will equal the population average c. Means that a table of random numbers was used to dictate the selection d. Is an almost meaningless theoretical requirement 4.43. Which of the following is a discrete probability distribution? a. Normal b. Weibull c. Binomial d. Lognormal 4.44. What is the general use of an R chart? a. To determine if the process is in control b. To determine if the process mean is in control c. To determine if the process variation is in control d. To determine the variance of the process 4.45. The instantaneous rate of failure of units, having survived up to the beginning of a particular time interval of interest, represented by the: is a. Density function b. Hazard function c. Reliability function. d. Exponential function 4.46. Which of the following is probability distribution? a. Weibull b. Hypergeometric c. Binomial d. Poisson a continuous 4.47. A recent survey of 347 people that purchased laptop computer found that 6 of the laptops were defective. Based on this survey, what is the probability of getting a defective laptop computer? a. 0.003 b. 0.017 4.50. 4.48. The equation below represents: Cpv= USL - X 30R X-LSL 30R a. The limits for an X-bar control chart b. The limits for a range chart c. The process capability adjusted for centering d. The probability of meeting specification c. 0.060 d. 0.983 4.49. Which of the following statements is true about the failure rate for a system whose time to failure distribution is Weibull with shape parameter b= 2? or a. It remains constant b. It increases at a constant rate c. It increases at an increasing rate d. It increases at a decreasing rate a. 30.2 ± 4.11 ppm b. 30.2 3.96 ppm c. 30.2 ± 4.00 ppm d. 30.2 ± 3.36 ppm Six independent samples are taken of smokestack gas. The mean value of a critical pollutant was 30.2 ppm for the six samples, with a standard deviation S 5 ppm. Assuming that the samples were taken at random times, what is the 90% confidence interval for the proportion of the critical pollutant in the smokestack gas? 4.51. Laboratory tests of a new polymer prototype yielded the following proportions of a critical compound: 4.2 ppm, 4.1 ppm, 4.7 ppm, 4.9 ppm, 5.3 ppm What is the sample standard deviation? a. 0.498 c. 0.475 b. 0.464 d. 0.445