Question 1

Which of the following statements concerning control chart limits is true?

Accepted Answer

The answer of Which of the following statements concerning control...

Question 2

The formulas for determining the upper and lower control limits are based on the number of standard deviations, z, from the process average. Management usually selects a z value of _______because it wants a high probability that these sample values will fall within the control limits.

Accepted Answer

Management usually selects a z value of three because it provides a high level of confidence (99.73%) that the process is within control limits. A z value of one or two would provide lower levels of confidence, while a z value of six would be overly stringent and result in a high number of false positives.

Question 3

Consider a production process that produces batteries. A quality engineer has taken 20 samples each containing 100 batterieslight bulbs. The total number of defective batteriesunits observed over the 20 samples is 1200. The UCL for the control chart constructed using two sigma is
a. 0..088
b. 0.094
c. 0.104
d. 0.11660

Accepted Answer

The answer of Consider a production process that produces batteries....

Question 4

Special cause (nonrandom) variation in a process is more likely to be detected with

Accepted Answer

Narrow control limits make it easier to detect nonrandom variation, including special causes. This is because narrower limits make it more difficult for data points to fall within the control limits and thus any points outside of the limits are more likely to be due to special causes. Wider control limits make it more difficult to detect nonrandom variation as data points are more likely to fall within the limits, including those that may be due to special causes. Specification limits do not impact the detection of nonrandom variation as they relate to the customer's requirements and not the process itself.

Question 5

The basic purpose of control charts include(s)

Accepted Answer

Both establishing control limits for a process and monitoring the process to indicate when it is out of control are basic purposes of control charts. Control charts help identify when a process is in a state of statistical control or stable, and when it is out of control or unstable, indicating that corrective action may be necessary. The control limits serve as a basis for identifying when a process is out of control by showing the range within which the process is expected to fluctuate in a stable state.

Question 6

Consider a production process that produces tires. A quality engineer has taken 15 samples, each containing 200 tires. The total number of defective tires over the 15 samples is 340. The centerline for the control chart is

Accepted Answer

The centerline for a p-chart is calculated as the overall proportion of defects in the process. In this case, the overall proportion of defective tires is calculated as (340/15*200) = 0.1133 or 0.11 (rounded to two decimal places). Therefore, the centerline for the control chart is 0.11. Hence the correct choice is B.

Question 7

58. A company randomly selects 100 light bulbs every day for 40 days from its production process. If 600 defective light bulbs are found in the sampled bulbs then the estimate for the process average percent defective would be

Accepted Answer

The estimate for the process average percent defective can be calculated as follows:
Total number of bulbs sampled = 100 x 40 = 4000
Percent defective in the sampled bulbs = (600/4000) x 100 = 15%
Therefore, the estimate for the process average percent defective is 0.150 or 15% (Option C).

Question 8

Which of the following statements is TRUE?

Accepted Answer

Wider control limits (larger Z) mean that more variation is allowed before the process is considered out of control, making it more likely for the process to be in control.

Question 9

Control charts are typically used at the ___________ of a process.

Accepted Answer

The answer of Control charts are typically used at the...

Question 10

Consider a production process that produces batteries. A quality engineer has taken 20 samples each containing 100 batterieslight bulbs. The total number of defective batteriesunits observed over the 20 samples is 1200. The sample standard deviation is
a. 0.0183
b. 0.0224
c. 0.0265
d. 0.05210

Accepted Answer

The answer of Consider a production process that produces batteries....

Question 11

Which of the following is NOT not a characteristic of a control chart?

Accepted Answer

The answer of Which of the following is NOT not...

Question 12

A variable measure is a product characteristic such as

Accepted Answer

Temperature is a variable measure because it can be quantified and measured on a continuous scale, unlike the other options which are qualitative attributes.

Question 13

57. If a sample of 40units of output found 500 defects, then the 3-sigma upper control limit for the chart would be

Accepted Answer

The answer of 57. If a sample of 40units of...

Question 14

Which of the following is NOT not a primary purpose of statistical process control?

Accepted Answer

Statistical process control is used to monitor and control a process over time. The primary purposes of statistical process control are to establish control limits, detect special cause variations, and determine when a process is not in control. The identification of specification limits is not a primary purpose of statistical process control, although it may be part of the overall quality control process.

Question 15

Consider a production process that produces batteries. A quality engineer has taken 20 samples each containing 100 batterieslight bulbs. The total number of defective batteriesunits observed over the 20 samples is 1200. The LCL for the control chat constructed using two sigma is

Accepted Answer

The LCL (Lower Control Limit) for a p-chart is calculated using the formula: LCL = p̄ - 2 * sqrt((p̄(1-p̄))/n), where p̄ is the average proportion of defects (1200 defects / 2000 total units = 0.6) and n is the sample size (100). Calculating this gives LCL = 0.0406.

Question 16

Which of the following services can be measured and monitored with control charts?

Accepted Answer

Control charts are a tool used in statistical process control to monitor processes and ensure they are operating within acceptable limits. Any service that involves a process can be measured and monitored with control charts, including hospitals, airlines, and banks. Therefore, all answer choices are correct.

Question 17

59. A company randomly selects 100 light bulbs every day for 40 days from its production process. If 600 defective light bulbs are found in the sampled bulbs then the 3-sigma lower control limit would be

Accepted Answer

The answer of 59. A company randomly selects 100 light...

Question 18

Consider a production process that produces batteries. A quality engineer has taken 20 samples each containing 100 batterieslight bulbs. The total number of defective unitsbatteries observed over the 20 samples is 1200. The centerline for the control chart constructed using z equal to two is
a. 0.03
b. 0.04
c. 0.05
d. 0.10

Accepted Answer

The answer of Consider a production process that produces batteries....

Question 19

When a control chart is first developed, if the process is found to be out of control,

Accepted Answer

If the process is found to be out of control, it is important to examine the process and make corrections before a new control chart is constructed. Simply utilizing the control chart without addressing the root cause of the out of control situation will not solve the problem.

Question 20

To monitor the number of blemishes on a polished surface a company randomly selects 10 units of output from its process and counts the number of blemishes on each unit. The sample results are shown below  Given the sample information above, the average number of defects per unit for this process would be

Accepted Answer

To find the average number of defects per unit, we need to add up the number of defects for all 10 units and divide by 10 (the number of units sampled).

Adding up the number of defects for all 10 units: 
0 + 0 + 0 + 40 + 1 + 50 + 0 + 20 + 20 + 10 = 141

Dividing by 10: 
141/10 = 14.1

Therefore, the average number of defects per unit is 16 (rounded to the nearest whole number). The best choice is C.

Quiz 3: Statistical Process Control

Which of the following statements concerning control chart limits is true?

The formulas for determining the upper and lower control limits are based on the number of standard deviations, z, from the process average. Management usually selects a z value of _______because it wants a high probability that these sample values will fall within the control limits.

Special cause (nonrandom) variation in a process is more likely to be detected with

The basic purpose of control charts include(s)

Consider a production process that produces tires. A quality engineer has taken 15 samples, each containing 200 tires. The total number of defective tires over the 15 samples is 340. The centerline for the control chart is

58. A company randomly selects 100 light bulbs every day for 40 days from its production process. If 600 defective light bulbs are found in the sampled bulbs then the estimate for the process average percent defective would be

Which of the following statements is TRUE?

Control charts are typically used at the ___________ of a process.

Consider a production process that produces batteries. A quality engineer has taken 20 samples each containing 100 batterieslight bulbs. The total number of defective batteriesunits observed over the 20 samples is 1200. The sample standard deviation is a. 0.0183 b. 0.0224 c. 0.0265 d. 0.05210

Which of the following is NOT not a characteristic of a control chart?

A variable measure is a product characteristic such as

57. If a sample of 40units of output found 500 defects, then the 3-sigma upper control limit for the chart would be

Which of the following is NOT not a primary purpose of statistical process control?

Consider a production process that produces batteries. A quality engineer has taken 20 samples each containing 100 batterieslight bulbs. The total number of defective batteriesunits observed over the 20 samples is 1200. The LCL for the control chat constructed using two sigma is

Which of the following services can be measured and monitored with control charts?

59. A company randomly selects 100 light bulbs every day for 40 days from its production process. If 600 defective light bulbs are found in the sampled bulbs then the 3-sigma lower control limit would be

When a control chart is first developed, if the process is found to be out of control,