Question 1

In manufacturing, quality control is generally applied at the receiving stage from suppliers, during various production processes, and at the finished-goods stage.

Accepted Answer

Quality control is generally applied throughout the manufacturing process, including at the receiving stage from suppliers, during various production processes, and at the finished-goods stage.

Question 2

Common causes of variation generally accounts for about 80 to 90 percent of the observed variation within a process.

Accepted Answer

This statement is true. Common causes of variation are natural variations that are part of a process and account for the majority of the variation.

Question 3

The 1:10:100 Rule supports the need for control and a focus on prevention by building quality at the source.

Accepted Answer

The 1:10:100 Rule emphasizes the importance of building quality at the source, which means preventing defects from occurring rather than detecting and correcting them later. This is achieved by investing in prevention activities, which can help identify and eliminate the root cause of defects. The rule suggests that the cost of preventing a defect is much less than the cost of correcting it after it occurs, with the ratio of 1:10:100 representing the average cost of prevention, detection, and correction. Therefore, the rule supports the need for control and a focus on prevention.

Question 4

Flaws are counted on a standard steel plate (sheet). Each sheet has the exact same dimensions. If 10 sheets are selected at random and the number of flaws per sheet is as follows, determine the lower and upper control limits. $\begin{array} { | c | c | } 
\hline \text { Sheet } & \text { Number of Flaws } \
\hline 1 & 3 \
\hline 2 & 1 \
\hline 3 & 3 \
\hline 4 & 0 \
\hline 5 & 2 \
\hline 6 & 2 \
\hline 7 & 0 \
\hline 8 & 1 \
\hline 9 & 1 \
\hline 10 & 2 \
\hline
\end{array}$ The upper control limit (UCL) for the steel plate control chart is _____.
A) less than 3
B) more than or equal to 3 but less than 4
C) more than or equal to 4 but less than 5
D) more than or equal to 5 but less than 6

Accepted Answer

The answer of Flaws are counted on a standard steel...

Question 5

With good management, all variability of output from any goods- or service-producing process can be eliminated.

Accepted Answer

It is not possible to completely eliminate all variability in an output from any process, as there will always be some degree of randomness or unpredictability. However, good management practices can help to reduce and control variability to a certain extent.

Question 6

In-process quality control is typically performed by the employees who run the processes.

Accepted Answer

In-process quality control is a responsibility of the employees who run the processes. They are responsible for monitoring and ensuring that the products are of the desired quality during the manufacturing process.

Question 7

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $$z = 3$$ . Suppose a sample had 0.054 defectives. What would be the best action to take in this scenario?
A) Nothing; it appears to be random variation.
B) Look for assignable causes.
C) Change z to 2 and take another sample.
D) Change z to 4 and continue sampling.

Accepted Answer

Given a z-value of 3, the control limits for the p-chart are calculated using the average proportion of defects (p) and the standard deviation of the proportion (sqrt[p(1-p)/n]), where n is the sample size. The upper control limit (UCL) is p + z*sqrt[p(1-p)/n], and the lower control limit (LCL) is p - z*sqrt[p(1-p)/n]. With p = 0.015, n = 100, and z = 3, the UCL is significantly lower than 0.054, indicating that the sample with 0.054 defectives is outside the control limits. This suggests that the process is not in control, and it is not due to random variation. Therefore, the best action is to look for assignable causes of the variation.

Question 8

Quality at the source focuses on supplier quality at the beginning of a value chain.

Accepted Answer

Quality at the source is a philosophy that emphasizes the responsibility of each employee to ensure quality in their own work, rather than relying on a separate quality control department or focusing solely on supplier quality.

Question 9

A supplier is producing a machined part for the transmission of a vehicle. The upper specification limit is 0.125 cm, and the lower specification limit is 0.085. The process standard deviation for the process that makes this part is 0.008, and the process average is 0.105. What conclusion can be drawn from these process capability data?
A) The process is centered and capable.
B) The process is not centered and capable.
C) The process is centered and not capable.
D) The process is not centered and not capable.

Accepted Answer

The answer of A supplier is producing a machined part...

Question 10

The goal of statistical process control (SPC) is to help identify and eliminate unwanted causes of variation.

Accepted Answer

The goal of statistical process control is indeed to identify and eliminate unwanted causes of variation, in order to improve the quality and consistency of a process. SPC involves using statistical methods to analyze data and monitor a process over time, with the aim of identifying when the process is out of control and taking corrective action to bring it back into a state of statistical control. By reducing variation and maintaining consistent performance, SPC can help organizations improve efficiency, reduce waste, and enhance customer satisfaction.

Question 11

A key element of a control system is the ability to measure performance and compare it to a performance standard.

Accepted Answer

Measuring performance and comparing it to a performance standard is a fundamental aspect of control systems, as it allows for the identification of any deviations or variations in performance that may require corrective action.

Question 12

It generally costs more to correct an error or defect at the design stage than after it has reached the customer.

Accepted Answer

It generally costs less to correct an error or defect at the design stage than after it has reached the customer, as changes at later stages often require more effort and resources, including potential recalls and damage to reputation.

Question 13

A supplier is producing a machined part for the transmission of a vehicle. The upper specification limit is 0.135 cm, and the lower specification limit is 0.075. The process standard deviation for the process that makes this part is 0.005, and the process average is 0.105. What conclusion can be drawn from these process capability data?
A)The process is centered and capable.
B)The process is not centered and capable.
C)The process is centered and not capable.
D)The process is not centered and not capable.

Accepted Answer

The process standard deviation and the difference between the upper and lower specification limits must be taken into account when evaluating process capability. Using the process capability index (Cpk), we can determine whether the process is centered and capable. In this case, since the process average is within the specification limits and the Cpk value is greater than 1 (Cpk = 2.0), we can conclude that the process is both centered and capable of producing parts that meet the specifications. Therefore, the best choice is A.

Question 14

The time to check out guests at a hotel front desk was measured over the course of several weeks. Management believes that the target time for checking out guests should be between 2 and 3 minutes with a target of 2.5 minutes. The data gathered for the actual process had a mean time of 2.75 minutes with a standard deviation of 0.45 minutes. Find and interpret Cp, Cpl, Cpu, and Cpk in the context of this situation. Which one of the following statements is TRUE?
A) The process is centered and not capable.
B) The process is centered and capable.
C) The process is not centered and capable.
D) The process is not centered and not capable.

Accepted Answer

The process capability indices Cp, Cpl, Cpu, and Cpk help in understanding how well a process can meet its specifications. Cp measures the overall capability of the process to meet its specifications without considering its mean. Cpl and Cpu measure the capability of the process to meet its lower and upper specifications, respectively, taking into account the process mean. Cpk is the minimum of Cpl and Cpu, indicating the process's capability to meet the closest specification limit.Given data:- Target time: 2.5 minutes- Actual mean time: 2.75 minutes- Standard deviation: 0.45 minutes- Lower specification limit (LSL): 2 minutes- Upper specification limit (USL): 3 minutesCp = (USL - LSL) / (6σ) = (3 - 2) / (6*0.45) = 1 / (2.7) ≈ 0.37Cpl = (mean - LSL) / (3σ) = (2.75 - 2) / (3*0.45) ≈ 0.56Cpu = (USL - mean) / (3σ) = (3 - 2.75) / (3*0.45) ≈ 0.19Cpk = min(Cpl, Cpu) = 0.19Interpretation:- Cp < 1 indicates the process is not capable of meeting the specifications if it were centered.- The process mean is not centered between the LSL and USL, as it is closer to the USL.- Cpk being the lowest among the indices and less than 1 indicates the process is not capable of consistently meeting the specifications.Therefore, the process is not centered (due to the mean not being at the target of 2.5 minutes) and not capable (since Cpk < 1) of meeting the specifications reliably.

Question 15

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $$z = 3$$ . Suppose a sample had 0.044 defectives. What would be the best action to take in this scenario?
A) Nothing; it appears to be random variation.
B) Look for assignable causes.
C) Change z to 2 and take another sample.
D) Change z to 4 and continue sampling.

Accepted Answer

The answer of Historically, the average proportion of defective bars...

Question 16

A bottling process sometimes results in overfills or underfills. Overfills are especially damaging to the equipment. Which process capability index would this company most want to monitor? A) C_p B) C_pl C) C_pu D) C_pk

Accepted Answer

The process capability index that measures the upper specification limit (USL) deviation from the process mean is CPK, and the process capability index that measures the lower specification limit (LSL) deviation from the process mean is CPL. However, in this scenario, the company is specifically concerned with the overfills, which means they want to monitor the deviation from the USL only, not the LSL. Therefore, the best choice would be C_pu, which represents CPK (pu) for a one-sided specification limit (USL).

Question 17

Quality control ensures that a good or service conforms to specifications and meets customer requirements.

Accepted Answer

Quality control is a process implemented by organizations to ensure that their products or services meet specific requirements and specifications. This includes verifying that a product or service meets customer expectations and is of high quality.

Question 18

The lower and upper specification limits for a component are 4.20 and 4.30 ounces, respectively. The process standard deviation is .02, and the process average is 4.24 ounces. Which one of the following statements is TRUE? A) The C_p index indicates the process is centered. B) The C_p index indicates the process is not centered. C) The C_pk index indicates the process is centered. D) The C_pk index indicates the process is not centered.

Accepted Answer

The C_pk index is used for process capability when the process is not centered. Since the process average falls outside the specification limits (4.24 is less than the midpoint of 4.25), the process is not centered. Therefore, the correct index to use is the C_pk index, and the statement in option D is true.

Question 19

Common causes of variations generally accounts for about 10 to 15 percent of the observed variation within a process.

Accepted Answer

Common causes of variation, also known as natural or random causes, typically account for the majority of the observed variation in a process, often cited as around 85% to 95%, leaving special or assignable causes to account for the smaller remainder.

Question 20

Quality control of front-office operations in services uses the same techniques that are applied in manufacturing.

Accepted Answer

Quality control in front-office operations of services requires different techniques than those applied in manufacturing. Services are intangible and involve direct interaction with customers, making it difficult to apply some of the methods used in manufacturing such as statistical process control. Quality control in services typically involves activities such as gathering customer feedback, employee training, and continuous improvement of processes.

Quiz 16: Quality Control and Spc

In manufacturing, quality control is generally applied at the receiving stage from suppliers, during various production processes, and at the finished-goods stage.

Common causes of variation generally accounts for about 80 to 90 percent of the observed variation within a process.

The 1:10:100 Rule supports the need for control and a focus on prevention by building quality at the source.

With good management, all variability of output from any goods- or service-producing process can be eliminated.

In-process quality control is typically performed by the employees who run the processes.

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $z = 3$ . Suppose a sample had 0.054 defectives. What would be the best action to take in this scenario?

Quality at the source focuses on supplier quality at the beginning of a value chain.

The goal of statistical process control (SPC) is to help identify and eliminate unwanted causes of variation.

A key element of a control system is the ability to measure performance and compare it to a performance standard.

It generally costs more to correct an error or defect at the design stage than after it has reached the customer.

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $z = 3$ . Suppose a sample had 0.044 defectives. What would be the best action to take in this scenario?

A bottling process sometimes results in overfills or underfills. Overfills are especially damaging to the equipment. Which process capability index would this company most want to monitor?

Quality control ensures that a good or service conforms to specifications and meets customer requirements.

The lower and upper specification limits for a component are 4.20 and 4.30 ounces, respectively. The process standard deviation is .02, and the process average is 4.24 ounces. Which one of the following statements is TRUE?

Common causes of variations generally accounts for about 10 to 15 percent of the observed variation within a process.

Quality control of front-office operations in services uses the same techniques that are applied in manufacturing.

Quiz 16: Quality Control and Spc

In manufacturing, quality control is generally applied at the receiving stage from suppliers, during various production processes, and at the finished-goods stage.

Common causes of variation generally accounts for about 80 to 90 percent of the observed variation within a process.

The 1:10:100 Rule supports the need for control and a focus on prevention by building quality at the source.

With good management, all variability of output from any goods- or service-producing process can be eliminated.

In-process quality control is typically performed by the employees who run the processes.

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using z=3z = 3z=3 . Suppose a sample had 0.054 defectives. What would be the best action to take in this scenario?

Quality at the source focuses on supplier quality at the beginning of a value chain.

The goal of statistical process control (SPC) is to help identify and eliminate unwanted causes of variation.

A key element of a control system is the ability to measure performance and compare it to a performance standard.

It generally costs more to correct an error or defect at the design stage than after it has reached the customer.

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using z=3z = 3z=3 . Suppose a sample had 0.044 defectives. What would be the best action to take in this scenario?

A bottling process sometimes results in overfills or underfills. Overfills are especially damaging to the equipment. Which process capability index would this company most want to monitor?

Quality control ensures that a good or service conforms to specifications and meets customer requirements.

The lower and upper specification limits for a component are 4.20 and 4.30 ounces, respectively. The process standard deviation is .02, and the process average is 4.24 ounces. Which one of the following statements is TRUE?

Common causes of variations generally accounts for about 10 to 15 percent of the observed variation within a process.

Quality control of front-office operations in services uses the same techniques that are applied in manufacturing.

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $z = 3$ . Suppose a sample had 0.054 defectives. What would be the best action to take in this scenario?

Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using $z = 3$ . Suppose a sample had 0.044 defectives. What would be the best action to take in this scenario?