Question 1

A company produces a product which is designed to weigh 10 oz.,with a tolerance of + 0.5 oz.The process produces products with an average weight of 9.95 oz.and a standard deviation of 0.10 oz.According to the process capability ratio,is the process capable of meeting design specifications?

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Question 2

A company manufactures a product that has a design (nominal)target width of 5 inches with tolerances of + .05 inch.The process that produces the product has a mean of 4.995 inches and a standard deviation of 0.01 inch.The process capability ratio for this process is

Accepted Answer

Process capability ratio can be calculated using the formula:

Process Capability Ratio = (Upper Specification Limit – Lower Specification Limit) / (6 x Standard Deviation)

Given, 
Design target width = 5 inches 
Tolerance = ± 0.05 inches 
Mean = 4.995 inches 
Standard deviation = 0.01 inches

The upper specification limit is 5.05 inches (5 + 0.05) and the lower specification limit is 4.95 inches (5 – 0.05).

Substituting the given values in the formula, we get:

Process Capability Ratio = (5.05 – 4.95) / (6 x 0.01) 
= 0.1 / 0.06 
= 1.67

A process capability ratio of 1.67 indicates that the process is capable of producing products within the specified tolerance limits with good consistency. Therefore, the best choice is option D.

Question 3

What is the process capability ratio and how is it calculated?

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Question 4

Using control charts,how do we evaluate whether a process is in control?

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Question 5

Why are  and R-charts used together?

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Question 6

A company produces a product which is designed to weigh 10 oz.,with a tolerance of + 0.5 oz.The process produces products with an average weight of 9.95 oz.and a standard deviation of 0.10 oz.The process capability index for this process,with z = 3,is

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Question 7

A company produces a product which is designed to weigh 10 oz.,with a tolerance of + 0.5 oz.The process produces products with an average weight of 9.95 oz.and a standard deviation of 0.10 oz.The process capability ratio for this process,with z = 3,is

Accepted Answer

The process capability ratio is calculated as (USL - LSL) / (6 * sigma), where USL is the upper specification limit, LSL is the lower specification limit, and sigma is the standard deviation. In this case, the USL is 10.5 oz., the LSL is 9.5 oz., and the sigma is 0.10 oz. Therefore, the process capability ratio is (10.5 - 9.5) / (6 * 0.10) = 1.67.

Question 8

For the process to be capable of meeting design specification,the process capability index must be

Accepted Answer

A process capability index (such as Cpk or Cp) measures the ability of a process to produce output within specification limits. A value of 1.0 or greater indicates that the process is capable of meeting the design specification, while a value less than 1.0 indicates that the process is not capable. Therefore, the best choice is B, which states that the process capability index must be equal to or greater than one (1.0) for the process to be capable of meeting design specification.

Question 9

What is a c-chart and when is it used?

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Question 10

A company manufactures a product that has a design (nominal)target width of 5 inches with tolerances of + .05 inch.The process that produces the product has a mean of 4.995 inches and a standard deviation of 0.01 inch.The process capability index for this process is

Accepted Answer

The process capability index (Cpk) is calculated as the minimum of two ratios:

Cpk = min[(USL - mean)/3σ, (mean - LSL)/3σ]

where USL and LSL are the upper and lower specification limits, respectively.

In this case, the USL is 5.01 inches (5 + 0.01) and the LSL is 4.99 inches (5 - 0.01).

Substituting these values and the given mean and standard deviation into the formula, we get:

Cpk = min[(5.01 - 4.995)/(3 x 0.01), (4.995 - 4.99)/(3 x 0.01)]
    = min[0.5, 0.1667]
    = 0.1667

Since the minimum of the two ratios is less than 1, the process is not capable of meeting the specifications.

The best choice is therefore B, which is the only option that corresponds to a value less than 1.

Question 11

A company produces a product which is designed to weigh 10 oz.,with a tolerance of + 0.5 oz.The process produces products with an average weight of 9.95 oz.and a standard deviation of 0.10 oz.According to the process capability index

Accepted Answer

The process capability index (Cpk) compares the distance between the process mean and the nearest specification limit, in this case, the upper limit of 10 oz, to the variability of the process. A Cpk value of 1 or greater indicates that the process is capable of meeting design specifications. The given process has an average weight of 9.95 oz, which is within the tolerance range of 9.5-10.5 oz. Moreover, the standard deviation of 0.10 oz is smaller than the tolerance range of 0.5 oz. Therefore, the process is capable of meeting the design specifications.

Question 12

Briefly discuss attribute and qualitative variable quality measures.

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Quiz 3: Statistical Process Control