In the construction industry, the initial inspection of tie beams is estimated to cost $0.20 per unit. If, however, a nonconforming beam is allowed for construction purposes, the unit cost of rectifying and replacing it is $50. What inspection policy should be followed, using Deming’s kp rule, if the non-conformance rate of beams is 0.5%? What is the average savings in total inspection costs if 100% inspection is used as opposed to no inspection?
> Refer to Exercise 12-19. Consider the following two contrasts of totals: (1) difference between the totals for training programs 1 and 3; (2) difference between the totals for the sum of training programs 1 and 3 and twice that of training program 2. (a)
> Refer to Exercise 12-19. Find a 90% confidence interval for the difference in the mean effectiveness of program 1 and the average of that using programs 2 and 3. Data from Exercise 12-19: Three training programs are being considered for auditors in an a
> Refer to Exercise 12-18. (a) Is there a difference in the mean number of passengers bumped using software packages 1 and 2 from that using software packages 3 and 4? Test at the 10% level of significance. (b) Find a 95% confidence interval for the contra
> Refer to Exercise 12-17. (a) Is there a difference between the mean degree of lateness of company 3 and that of the averages of companies 1 and 2? Test at the 5% level of significance. (b) Find a 90% confidence interval for the contrast defined in part (
> Consider Example 12-4 concerning the efficiency of synthetic fuel for which the factors are an additive and a catalyst. The original data are given in Table 12-19. The experiment is conducted using only five randomly chosen automobiles (A, B, C, D, and E
> Two controllable factors, temperature and pressure, are each kept at three levels to determine their impact on the ductility of an alloy being produced. The temperature levels are 150, 250, and 300 °C, respectively. Pressure is controlled at 5
> A consulting firm wishes to evaluate the performance of four software packages (A, B, C, and D) as measured by the computational time. The experimenter wishes to control for two variables: the problem type and the operating system configuration used. Fou
> A doctor is contemplating four types of diet to reduce the blood sugar levels of patients. Because of differences in the metabolism of patients, the doctor categorizes the patients into five age groups. From each age group, four patients are selected and
> Three training programs are being considered for auditors in an accounting firm. The success of the training programs is measured on a rating scale from 0 to 100, with higher values indicating a desirable program. The company has categorized its auditors
> An airline is interested in selecting a software package for its reservation system. Even though the company would like to maximize use of its available seats, it prefers to bump as few passengers as possible. It has four software packages to choose from
> A 95% confidence interval for the mean thickness of a part in millimetres is (10.2, 12.9). Interpret this interval.
> A large retail company has to deliver its goods to distributors throughout the country. It has been offered trial-run services by three transportation companies. To test the efficiency of these three companies, it randomly assigns its outgoing product sh
> Refer to Exercise 11-8 concerning the redesigned remote control unit with 25 components in series. If it is desired that the remote unit has a reliability of 0.996 for 3000 hours of operation, what should the failure rate be for each component? What shou
> Refer to Exercise 11-31. Test the null hypothesis of equality of the survival functions of the two groups using a level of significance of 0.05. Data from Exercise 11-31: Two groups of samples of patients were randomly selected from a county. The first
> Two groups of samples of patients were randomly selected from a county. The first group (Group 1) had no history of a chronic disease while the second group (Group 2) had a positive history. The selected patients were observed for a period of 15 years. S
> Refer to Exercise 11-29. If failed items are not replaced during the test, determine the plan using Handbook H-108. Data from Exercise 11-29: In a time-terminated life testing plan, it is desired to reject lots with a mean life of 1500 hours with a prob
> In a time-terminated life testing plan, it is desired to reject lots with a mean life of 1500 hours with a probability of 0.95 and reject lots with a mean life of 7500 hours with a probability of 0.10. The test is to be terminated by 2500 hours. Items th
> Refer to Exercise 11-27. Find the appropriate plan using Handbook H-108 if failed items are not replaced during the test. Data from Exercise 11-27: A time-terminated life testing plan is desired that will accept lots with a mean life of 6000 hours with
> A time-terminated life testing plan is desired that will accept lots with a mean life of 6000 hours with a probability of 0.99 and will accept lots with a mean life of 2000 hours with a probability of 0.10. The test should be terminated by 1200 hours. It
> Refer to Exercise 11-25. If failed items are replaced with similar items, determine a life testing plan using Handbook H-108. Data from Exercise 11-25: A time-terminated life testing plan is to be found that will reject lots that have a mean life of 140
> A time-terminated life testing plan is to be found that will reject lots that have a mean life of 1400 hours with a probability of 0.05. The rejection number is 7, with a sample size of 35. Determine the plan using Handbook H-108 if the time to failure i
> Distinguish between a hypergeometric and a binomial random variable.
> Refer to Exercise 11-23. Suppose that items that fail during the test are immediately replaced with similar items. Determine the life testing plan using Handbook H-108. Data from Exercise 11-23: A time-terminated life testing plan is to be found that wi
> A time-terminated life testing plan is to be found that will reject lots with a mean life of 1500 hours with a probability 0.05 and accept lots with a mean life of 600 hours with a probability of 0.10. Items that fail during the test are not replaced. De
> A life testing plan is to be terminated after the third failure. It should accept a lot that has an acceptable mean life of 600 hours with a probability of 0.99. Failed items are not replaced during the test. A sample of eight items is chosen, and three
> Refer to Exercise 11-20. Assume that failed items are immediately replaced during the test. Using Handbook H-108, what is your recommendation on the lot? Data from Exercise 11-20: A life testing plan is to be terminated after the eighth failure. It shou
> A life testing plan isto be terminated after the eighth failure. It should reject a lot that has an acceptable mean life of 900 hours with a probability of 0.10. Items that fail during the test are not replaced. A sample of 15 items is placed on test wit
> A sample of 25 relays is chosen for life testing. The time to failure of a relay is exponentially distributed. The test is terminated after 800 hours, with five failures being observed at times 610, 630, 680, 700, and 720 hours. Failed items are not repl
> Refer to Exercise 11-17. Assume that each failed item is replaced with an identical unit. Estimate the mean time to failure and the failure rate. Find a 90% confidence interval for the mean time to failure. Data from Exercise 11-17: A sample of 20 diode
> A sample of 20 diodes is chosen for life testing. The time to failure of the diodes is exponentially distributed. The test is terminated after six failures, with no replacement of the failed items. The failure times (in hours) of the six diodes are 530,
> Construct the OC curve for the life testing plan n= 6, T =900 hours, c =3. For a producer’s risk of 0.05, what is the associated quality of batches as indicated by their mean life? For a consumer’s risk of 0.10, what is the associated quality level of ba
> Refer to Exercise 11-13 and the system shown in Figure 11-14. Suppose that component B is a standby component. Find the reliability of the system after 1000 hours. What is the mean time to failure? Data from Exercise 11-13: Consider the seven-component
> State the null and alternative hypotheses in the following situations by defining the parameters used. Also, state any assumptions that you need to make to conduct the test: (a) The Postal Service wishes to prove that the mean delivery time for packages
> A standby system has a basic unit with four standby components. The time to failure of each component has an exponential distribution with a failure rate of 0.008/hour. For a 400-hour operation period, find the reliability of the standby system. What is
> Consider the seven-component system shown in Figure 11-14. Assume that the time to failure for each component has an exponential distribution. The failure rates are as follows: λA = 0.0005/hour, λB= 0.0005/hour, λC=
> Consider the seven-component system shown in Figure 11-14. The reliabilities of the components are as follows: RA = 0.96, RB= 0.92, RC=0.94, RD = 0.89, RE = 0.95, RF=0.88, RG =0.90. Find the reliability of the system. If you had a choice of improving sys
> Refer to Exercise 11-10. Each component has a time to failure that is exponentially distributed, with a mean time to failure of 3000 hours. Find the reliability of the subassembly for 2500 hours of operation. What is the mean time to failure of the subas
> Four components A, B, C, and D are placed in parallel to make a subassembly in a circuit board. The reliabilities of A, B, C, and D are 0.93, 0.88, 0.95, and 0.92, respectively. Find the reliability of the subassembly.
> A cereal manufacturer who claims to meet certain mineral and vitamin requirements has a minimum specification of 25% for the iron content. The standard deviation of the iron content is estimated to be 3%. It is preferred to accept batches that are 1.5% n
> The thickness of silicon wafers is an important characteristic in microelectronic circuits. The upper specification limit for the thickness is 0.015 mm. It is estimated that the standard deviation of the thickness of wafers is 0. 0014mm.We wish to accept
> A dairy has to control the amount of butterfat in its low-fat milk. The upper specification limit of the fat content is 4 g for 4-L containers. The standard deviation of the fat content for these containers is estimated to be 0.5 g. It is desired to acce
> Unleaded gasoline must meet certain federal standards. The octane number for a particular brand must be at least 89. The standard deviation of the octane number is estimated to be 4. It is preferred to accept shipments for which the average octane number
> Refer to Exercise 10-52 regarding the proportion of carbon monoxide in exhaust gases, which has an upper specification limit of 0.30. Ifthe average carbon monoxide content is 1 standard deviation below the upper specification limit, the devices should be
> Distinguish between the use of the mean, median, and mode in quality control applications. When do you prefer to use the trimmed mean?
> The proportion of carbon monoxide in exhaust gases has an upper specification limit of 0.30. Emission control devices are being tested to meet such requirements. We wish that devices with an average carbon monoxide content of 0.15 or less be accepted 95%
> The length of connector pins has an upper specification limit of 45 mm and a lower specification limit of 40 mm. It is desirable that lots with a mean such that 8% of the product is nonconforming, either above the upper specification limit or below the l
> The tensile strength of an alloy has double specification limits. If the process average tensile strength is below 800 kg/cm2 or above 1200 kg/cm2, it is desired to accept such lots with a probability of 0.08. For lots with a process average of 1000 kg/c
> The lower specification limit for the breaking strength of yarns is 25 g. The distribution of the breaking strength of yarns is normal with a variance of 6. It is desirable that lots with a mean such that 3% of the product is nonconforming be accepted 94
> The upper specification limit for the resistance of coils is 30 Ω. The distribution of coil resistance is known to be normal with a standard deviation of 5 Ω. It is preferred to reject batches that have a mean of 2.3 standard deviations below the upper s
> Refer to Exercise 10-44. lf the monthly production is 2000 units, what is the average savings in total inspection costs when using Deming’s kp rule as opposed to 100% inspection? Data from Exercise 10-44: In Exercise 10-43, if the initial inspection cos
> Refer to Exercise 10-43, Suppose that the monthly production is 3000 units. What is the average savings in total inspection costs per month when using the policy found from Deming’s kp rule as opposed to no inspection? Data from Exercise 10-43: The init
> In Exercise 10-43, if the initial inspection costs of the transmission systems are $1.00 per unit, what inspection policy should be followed using Deming’s kp rule? Data from Exercise 10-43: The initial inspection of transmission systems in automobiles
> The initial inspection of transmission systems in automobiles is estimated to cost $0.50 per unit. If a nonconforming transmission is allowed in the assembly, the unit cost to eventually disassemble and replace it is $225. The estimated proportion noncon
> Explain the different types of measurement scales and give examples in the following situations: (a) Gallons of water to put out a fire by the fire department (b) Response time of an ambulance (c) Test score in an examination (d) Customer product prefere
> A sequential sampling plan is to be used. It is desirable to have a producer’s risk of 0.05 at AQL= 0.008 and a consumer’s risk of 0.07 at LQL= 0.082. Determine the equations for the acceptance and rejection lines. What is the first opportunity to reject
> The equations for the acceptance and rejection lines for a sequential sampling plan are given as follows: What is the first opportunity to reject? What is the first opportunity to accept?
> A chain sampling plan is used with a sample size of 5 and a parameter i of 3. If lots have a proportion nonconforming of 0.06, find the probability of accepting such lots.
> Find a Dodge–Romig single sampling plan if the lot size is 600, the process average is 1.4% nonconforming, and AOQL=3%. Determine and interpret the LQL for the plan.
> Find a Dodge–Romig single sampling plan if the lot size is 2200 and LQL = 5.0%. Determine and interpret the AOQL for the plan.
> Find a Dodge–Romig single sampling plan if the lot size is 900, LQL= 5% nonconforming, and the process average is 0.8% nonconforming. What is the AOQL for the plan? Interpret it.
> Refer to Exercise 10-33. Find the sampling plan if it is desired to accept batches that are 5% nonconforming with a probability of 0.5. Data from Exercise 10-33: A double sampling plan is desired that has a producer’s risk of 0.05 at AQL =1.8% nonconfor
> Refer to Exercise 10-33. Find the double sampling plan if the second sample is to be twice as large as the first sample and the consumer’s stipulation is to be satisfied exactly. Data from Exercise 10-33: A double sampling plan is desired that has a pro
> It is desired to accept lots that are 9.5% nonconforming with a probability of 0.10 and to accept lots that are 2.3% nonconforming with a probability of 0.95. Find a double sampling plan for a lot size of 2000 if the second sample is to be twice as large
> A double sampling plan is desired that has a producer’s risk of 0.05 at AQL =1.8% nonconforming and a consumer’s risk of 0.10 at LQL =8.5% nonconforming. The lot size is 1500, and the sample sizes are assumed to be equal. Find the sampling plan if the pr
> Explain the difference between accuracy and precision of measurements. How do you control for accuracy? What can you do about precision?
> Refer to Exercise 10-30. What is the average sample number of incoming lots that are 2% nonconforming? What is the average total inspection for this quality level of 2% nonconforming? Data from Exercise 10-30: Consider a double sampling plan given by th
> Consider a double sampling plan given by the following parameters: N =2200, n1= 60, c1= 0, r1=5, n2= 100, c2= 6, r2=7. Find the probability of accepting lots that are 3% nonconforming. What is the probability of accepting a lot on the first sample? What
> Consider a double sampling plan given by the following parameters: N =1200, n1= 50, c1= 1, r1=4, n2= 110, c2= 5, r2=6. Find the probability of accepting lots that are 4% nonconforming. What is the probability of rejecting a lot on the first sample?
> A sampling plan is desired to have a producer’s risk of 0.05 at AQL =2.0% nonconforming and a consumer’s risk of 0.10 at LQL =7% nonconforming. Find the single sampling plan with the largest sample size. Find the single sampling plan with the smallest sa
> A sampling plan is desired to have a producer’s risk of 0.05 at AQL =1.3% nonconforming and a consumer’s risk of 0.10 at LQL= 7.1% nonconforming. Find the single sampling plan that meets the producer’s stipulation and comes as close as possible to meetin
> A sampling plan is desired to have a producer’s risk of 0.05 at AQL =0.9% and a consumer’s risk of 0.10 at LQL =6.5% nonconforming. Find the single sampling plan that meets the consumer’s stipulation and comes as close as possible to meeting the producer
> Determine single sampling plans that will accept lots that are 0.8% nonconforming with a probability of 0.96. Use acceptance numbers of 1, 3, and 4. If we desire batches that are 5% nonconforming to be accepted with a probability of no more than 0.04, wh
> Determine the single sampling plans that will accept lots that are 6% nonconforming 12% of the time. Use acceptance numbers of 1, 2, and 4. From a producer’s point of view, which of these plans would you choose?
> Determine the single sampling plans that will reject lots that are 1.3% nonconforming 8% of the time. Use acceptance numbers of 1, 3, and 5. From a consumer’s point of view, which of these three plans would you choose?
> A manufacturer is considering replacement of an existing machine that performs an operation on a part. The variable costs are $0.38 per piece on the existing machine and $0.05 per piece on the new machine. The cost of the new machine is $40,000, while th
> Find an expression for the probability of the union of three events that are mutually independent of each other.
> For the double sampling plan N= 2200, n1= 60, c1=1, r1=5, n2= 120, c2= 4, r2=5, construct the ASN curve. Within what range of proportion nonconforming values would you prefer the stated double sampling plan over a single sampling plan with n= 85, c= 2 in
> For the double sampling plan N = 2000, n1=80, c1= 1, r1=3, n2= 100, c2=2, r2= 3, construct and interpret the ASN curve. Suppose that process average nonconforming rate is 1.5%. Would you prefer the stated double sampling plan or a single sampling plan wi
> Construct the ATI curve for the sampling plan N = 1200, n= 50, c =1. Suppose that the process average nonconforming rate is 3%. Explain the value of ATI for that level of non-conformance.
> For the sampling plan N= 1500, n= 150, c= 3, construct the average outgoing quality curve. What is the AOQL? Interpret it.
> Suppose that desirable producer’s risk is 3% and consumer’s risk is 6%. Which of the plans described in Exercises 10-15 and 10-16 are preferable? Discuss your choice.
> Consider Exercise 10-15. Answer the same questions for the sampling plan N= 1500, n=200, c=3.Discussthe degree of protection of this plan compared to that in Exercise 10-15. Data from Exercise 10-15: Consider a single sampling plan with a lot size of 15
> Consider a single sampling plan with a lot size of 1500, sample size of 150, and acceptance number of 3. Construct the OC curve. If the acceptable quality level is 0.05% nonconforming and the limiting quality level is 6% nonconforming, describe the prote
> Refer to Exercise 9-49 on the laboratory turnaround time data. The facility wanted to compare its updated performance to another metropolitan facility serving the needs of similar patients. The other facility had a mean turnaround time of 35 minutes with
> Refer to Exercise 9-48. The quality improvement team, after a thorough study of the existing processes, recommended some procedural changes. Data collected after the changes yielded a mean turnaround time of 40 minutes with a standard deviation of 10 min
> Customers arrive at a department store randomly and independently. (a) What is an appropriate distribution for modelling the number of customers that arrive in a 2-hour period? (b) Under what situations might the stated assumptions not hold? (c) What inf
> The senior management in an urban bank is committed to improving its services. Discuss the specifics of quality of design, conformance, and performance in this context. Elaborate on possible basic needs, performance needs, and excitement needs of the cus
> A health care facility in a metropolitan area is interested in the efficiency of its laboratory turnaround time. Based on data collected over last year, the mean turnaround time was found to be 55 minutes with a standard deviation of 15 minutes. The faci
> Refer to Exercise 9-46. In order to boost product sales, the manager is contemplating the hiring of an additional sales staff. The added monthly cost of this hire will be $6000, but the expected monthly sales is projected to be $65,000 with a standard de
> For a marketing manager of a company, product sales in a specified market is of importance. Currently, for a brand-named product, the mean monthly sales are $50,000 with a standard deviation of $3500. Assuming normality of the distribution of monthly sal
> Refer to Exercise 9-42. The investment bank was able to identify a riskier strategy that projects a mean yield of 9.2% with a standard deviation of 2.4%. Assuming normality of distribution of yield rates, what is the lower capability index now if a targe
> Refer to Exercise 9-43 on the investment bank. Using the investment strategy that yields a mean yield of 7.0% with a standard deviation of 0.9%, what should a published goal of yield for customers be if the bank wants to be 95% sure of meeting that goal?
> Refer to Exercise 9-42. With the adoption of a slightly more conservative investment strategy, the bank forecasts a mean yield of 7.0% with a standard deviation of 0.9%. Assuming normality of distribution of yield rates, what is the lower capability inde
> An investment bank has been monitoring its return on investment for a certain category of its shareholders. Past data show a mean yield of 7.5% with a standard deviation of 1.5%. Assuming normality of distribution of yield rates, if senior management has
> Refer to Exercise 2-2. For each situation, explain what factors influence customer perception of quality and how they are to be managed. Data from Exercise 2-2: Discuss some service nonconformity and behavioural characteristics in the following areas: (
> Refer to Exercise 2-2. For each situation, discuss the ease or difficulty of measuring service quality. What are some remedial measures? Data from Exercise 2-2: Discuss some service nonconformity and behavioural characteristics in the following areas: (
> Discuss some service nonconformity and behavioural characteristics in the following areas: (a) Health care (b) Call center (c) Internal Revenue Service (d) Airline industry
> For each of the following areas, define appropriate quality characteristic(s) and parameters and indicate the hypotheses that you would test: (a) Effectiveness of a hospital in satisfying patients, employees, and shareholders (note that different hypothe
> Who is the customer in health care? Describe some of the customer’s needs.
> Consider the logistics company in Exercise 3-8. Conduct a quality function deployment analysis where the objective is to minimize delays in promised delivery dates. Data from Exercise 3-8: Consider a logistics company transporting goods on a global basi
