Question 1

A graph showing the probability of accepting the lot as a function of the percent defective in the lot is
A)a power curve
B)a control chart
C)an operating characteristic curve
D)None of these alternatives is correct.

Accepted Answer

An operating characteristic (OC) curve is used to show the performance of a sampling plan by plotting the probability of accepting a lot as a function of the percent defective in the lot. It helps to determine the appropriate sample size and acceptance criteria for a given inspection plan. A power curve is used to show the relationship between the power of a statistical test and the effect size or sample size. A control chart is used to monitor the process variability and detect any unusual behavior or out-of-control conditions. Therefore, the correct answer is C, an operating characteristic curve.

Question 2

A control chart that is used when the output of a production process is measured in terms of the percent defective is
A)a P chart
B)an X bar chart
C)a process chart
D)None of these alternatives is correct.

Accepted Answer

A P chart is used when the output of a production process is measured in terms of the proportion or percentage of defective items. It is a type of control chart that helps monitor and maintain the quality of a process by identifying any changes or out-of-control conditions in the proportion of defective items produced. The chart plots the proportion of defective items (p) against the sample number or time period, and provides control limits to help determine whether the process is in control or not. Therefore, a P chart is the best choice for this scenario.

Question 3

Variations in process output that are due to factors such as machine tools wearing out are
A)common causes
B)assignable causes
C)control causes
D)None of these alternatives is correct.

Accepted Answer

Variations in process output that are due to factors such as machine tools wearing out are known as assignable causes. These causes can be identified and corrected, which helps to improve the overall quality of the process. In contrast, common causes are due to natural variation in the process and cannot be eliminated. Control causes refer to factors that are deliberately manipulated in order to control the process output. None of these alternatives accurately describes the scenario presented in the question, so only option B is correct.

Question 4

Brakes Shop, Inc., is a franchise that specializes in repairing brake systems of automobiles. The company purchases brake shoes from a national supplier. Currently, lots of 1,000 brake shoes are purchased, and each shoe is inspected before being installed on an automobile. The company has decided instead of 100% inspection to adopt an acceptance sampling plan.
a.Explain what is meant by the acceptance sampling plan.
b.If the company decides to adopt an acceptance sampling plan, what kinds of risks are there?
c.The quality control department of the company has decided to select a sample of 10 shoes and inspect them for defects. Furthermore, it has been decided that if the sample contains no defective parts, the entire lot will be accepted. If there are 50 defective shoes in a shipment, what is the probability that the entire lot will be accepted?
d.What is the probability of accepting the lot if there are 100 defective units in the lot?

Accepted Answer

The answer of Brakes Shop, Inc., is a franchise that...

Question 5

A production process is considered in control if it processes at least 98.5% non-defective items. Samples of size 400 are used for the inspection process. Determine the upper and lower control limits for the P chart of defective elements.

Accepted Answer

The answer of A production process is considered in control...

Question 6

Normal or natural variations in process outputs that are due purely to chance are
A)common causes
B)assignable causes
C)control causes
D)None of these alternatives is correct.

Accepted Answer

Common causes are the natural variations inherent in a process, occurring due to random factors and are considered normal.

Question 7

A production process is set up to fill containers with 16 ounces of liquid. The standard deviation $\sigma$is known to be 0.5 ounces. The quality control department periodically selects samples of 25 containers and measures the contents. (Assume the distribution of filling volumes is normal.)
a.Determine the upper and lower control limits.
b.Explain the meaning of the values you found in part

Accepted Answer

The answer of A production process is set up to...

Question 8

The upper and lower control limits of the mean of a process are 606 and 594. Samples of size 225 are used for the inspection process. Determine the mean and the standard deviation for this process.

Accepted Answer

The answer of The upper and lower control limits of...

Question 9

In acceptance sampling, the risk of rejecting a good quality lot is known as
A)Consumer's risk
B)Producer's risk
C)a Type II error
D)None of these alternatives is correct.

Accepted Answer

The risk of rejecting a good quality lot is known as the producer's risk. This occurs when the lot is actually of acceptable quality, but the sampling procedure incorrectly identifies it as unacceptable and rejects it. This is also known as a Type I error. The consumer's risk, on the other hand, is the risk of accepting a poor quality lot, while a Type II error is the risk of failing to reject a poor quality lot.

Question 10

A production process that is in control has a mean (µ) of 200 and a standard deviation ($\sigma$) of 22.
Determine the lower and the upper control limits for sample sizes of 49.

Accepted Answer

The answer of A production process that is in control...

Question 11

The upper and lower control limits of the proportions of defectives of a process are 0.0803 and 0.0161
a.What has been the proportion of defectives in this process?
b.What has been the sample size?
c.Determine the standard error of proportion.

Accepted Answer

The answer of The upper and lower control limits of...

Question 12

Producer's risk is
A)the same as the Consumer's risk
B)the probability of Type II error
C)the probability of Type I error
D)None of these alternatives is correct.

Accepted Answer

The answer of Producer's risk is
A)the same as the Consumer's...

Question 13

If the lower-control limit of a P chart is negative,
A)a mistake has been made in the computations
B)use the absolute value of the lower limit
C)it is set to zero
D)None of these alternatives is correct.

Accepted Answer

In a P chart, if the calculated lower control limit is negative, it is set to zero because a proportion cannot be negative.

Question 14

Consumer's risk is
A)the same concept as the Producer's risk
B)the probability of Type II error
C)the probability of Type I error
D)None of these alternatives is correct.

Accepted Answer

Consumer's risk is the probability of accepting a lot of products that are not acceptable, which is equivalent to committing a Type II error.

Question 15

The upper and lower control limits of the proportions of defectives of a process are 0.33 and 0.27.
a.What has been the proportion of defectives in this process?
b.What has been the sample size?

Accepted Answer

The answer of The upper and lower control limits of...

Question 16

In acceptance sampling, the risk of accepting a poor quality lot is known as
A)Consumer's risk
B)Producer's risk
C)a Type I error
D)None of these alternatives is correct.

Accepted Answer

The risk of accepting a poor quality lot is known as consumer's risk. This means that a batch of products that are actually defective is accepted by the consumer or buyer, leading to the risk of dissatisfaction, waste, and potential harm.

Question 17

The quality control department of a company has decided to select a sample of 20 items from each shipment of goods it receives and inspect them for defects. It has been decided that if the sample contains no defective parts, the entire lot will be accepted.
a.What is the probability of accepting a lot that contains 10% defective items?
b.What is the probability of accepting a lot that contains 5% defective items?
c.What is the probability of rejecting a lot that contains 15% defective items?

Accepted Answer

The answer of The quality control department of a company...

Question 18

A group of items such as incoming shipments of raw material is called a(n)
A)sample plan
B)incoming control
C)lot
D)None of these alternatives is correct.

Accepted Answer

A lot is defined as a specific group of items that are identified as being related in some way. In this case, the group of incoming shipments of raw material would be considered a lot. A sample plan refers to a method of selecting a representative sample from a larger population, and incoming control may refer to the process of inspecting and verifying the quality of incoming shipments. Therefore, the best choice would be C - lot.

Question 19

The maximum number of defective items that can be found in the sample and still lead to acceptance of the lot is
A)the upper-control limit
B)the lower-control limit
C)the acceptance criterion
D)None of these alternatives is correct.

Accepted Answer

The acceptance criterion is the maximum allowable number of defects in a sample that still leads to acceptance of the lot. The upper and lower control limits are used in statistical process control to monitor the quality of a production process and do not directly relate to accepting or rejecting a lot.

Question 20

The upper and lower control limits of the proportions of defectives of a process are 0.13 and 0.07.
a.What has been the proportion of defectives in this process?
b.What has been the sample size?

Accepted Answer

The answer of The upper and lower control limits of...

Quiz 19: Statistical Methods for Quality Control

A graph showing the probability of accepting the lot as a function of the percent defective in the lot is

A control chart that is used when the output of a production process is measured in terms of the percent defective is

Variations in process output that are due to factors such as machine tools wearing out are

A production process is considered in control if it processes at least 98.5% non-defective items. Samples of size 400 are used for the inspection process. Determine the upper and lower control limits for the P chart of defective elements.

Normal or natural variations in process outputs that are due purely to chance are

The upper and lower control limits of the mean of a process are 606 and 594. Samples of size 225 are used for the inspection process. Determine the mean and the standard deviation for this process.

In acceptance sampling, the risk of rejecting a good quality lot is known as

A production process that is in control has a mean (µ) of 200 and a standard deviation ( $\sigma$ ) of 22. Determine the lower and the upper control limits for sample sizes of 49.

The upper and lower control limits of the proportions of defectives of a process are 0.0803 and 0.0161 a.What has been the proportion of defectives in this process? b.What has been the sample size? c.Determine the standard error of proportion.

Producer's risk is

If the lower-control limit of a P chart is negative,

Consumer's risk is

The upper and lower control limits of the proportions of defectives of a process are 0.33 and 0.27. a.What has been the proportion of defectives in this process? b.What has been the sample size?

In acceptance sampling, the risk of accepting a poor quality lot is known as

A group of items such as incoming shipments of raw material is called a(n)

The maximum number of defective items that can be found in the sample and still lead to acceptance of the lot is

The upper and lower control limits of the proportions of defectives of a process are 0.13 and 0.07. a.What has been the proportion of defectives in this process? b.What has been the sample size?

Quiz 19: Statistical Methods for Quality Control

A graph showing the probability of accepting the lot as a function of the percent defective in the lot is

A control chart that is used when the output of a production process is measured in terms of the percent defective is

Variations in process output that are due to factors such as machine tools wearing out are

A production process is considered in control if it processes at least 98.5% non-defective items. Samples of size 400 are used for the inspection process. Determine the upper and lower control limits for the P chart of defective elements.

Normal or natural variations in process outputs that are due purely to chance are

The upper and lower control limits of the mean of a process are 606 and 594. Samples of size 225 are used for the inspection process. Determine the mean and the standard deviation for this process.

In acceptance sampling, the risk of rejecting a good quality lot is known as

A production process that is in control has a mean (µ) of 200 and a standard deviation ( σ\sigmaσ ) of 22. Determine the lower and the upper control limits for sample sizes of 49.

The upper and lower control limits of the proportions of defectives of a process are 0.0803 and 0.0161 a.What has been the proportion of defectives in this process? b.What has been the sample size? c.Determine the standard error of proportion.

Producer's risk is

If the lower-control limit of a P chart is negative,

Consumer's risk is

The upper and lower control limits of the proportions of defectives of a process are 0.33 and 0.27. a.What has been the proportion of defectives in this process? b.What has been the sample size?

In acceptance sampling, the risk of accepting a poor quality lot is known as

A group of items such as incoming shipments of raw material is called a(n)

The maximum number of defective items that can be found in the sample and still lead to acceptance of the lot is

The upper and lower control limits of the proportions of defectives of a process are 0.13 and 0.07. a.What has been the proportion of defectives in this process? b.What has been the sample size?

A production process that is in control has a mean (µ) of 200 and a standard deviation ( $\sigma$ ) of 22. Determine the lower and the upper control limits for sample sizes of 49.