Question 1

What is the reliability of the three components connected in series shown below? 
A)0.799425
B)0.85000
C)0.91333
D)0.95000
E)2.79

Accepted Answer

The answer of What is the reliability of the three...

Question 2

A system is composed of four parts,J,K,L,and M.All four must function for the system to function.The four component reliabilities are .99,.98,.992,and .998.The designers are considering putting an 80% reliable backup at K.This backup will change the system reliability from ________ to ________.
A)0.9762;0.9605
B)0.9605;0.9762
C)0.9605;some smaller value
D)0.9605;0.996
E)0.98;0.99

Accepted Answer

The overall reliability of the system is the product of the reliabilities of the individual components. Without the backup at K, the system reliability would be 0.99 x 0.98 x 0.992 x 0.998 = 0.9605. 
Adding the backup at K, the overall reliability would be the probability that either K or the backup at K functions, which can be calculated as: 
(0.98 x 0.2) + (0.8 x 0.99) = 0.9796
Then, the overall reliability of the system with the backup is: 0.99 x 0.9796 x 0.992 x 0.998 = 0.9762. Therefore, the backup improves the system reliability from 0.9605 to 0.9762, and the correct answer is B.

Question 3

A system has three components in series with reliabilities 0.9,0.7,and 0.5.What is the system reliability?
A)0.315
B)0.500
C)0.700
D)0.900
E)2.100

Accepted Answer

The system reliability in series is found by multiplying the individual reliabilities:
0.9 × 0.7 × 0.5 = 0.315. Therefore, the answer is A.

Question 4

________ is the expected time between a repair and the next failure of a component,machine,process,or product.

Accepted Answer

The answer of ________ is the expected time between a...

Question 5

A system is composed of three components A,B,and C.All three must function for the system to function.There are currently no backups in place.The system has a reliability of 0.966.If a backup is installed for component A,the new system reliability will be:
A)unchanged.
B)less than 0.966.
C)greater than it would be if a backup were also installed for component B.
D)greater than 0.966
E)none of the above

Accepted Answer

If a backup is installed for component A, then the system will still function as long as either component B or C is working, in addition to the backup for component A. 
Therefore, the reliability of the new system with the backup for component A will be greater than 0.966.

Question 6

A redundant part decreases reliability if the reliability of the redundant part is lower than that of the part it is backing up.

Accepted Answer

The answer of A redundant part decreases reliability if the...

Question 7

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;all others completed the test.FR(%)is ________ and MTBF is ________.
A)10%;1/1820
B)90%;1/1820
C)10%;1820 hours
D)10%;1980 hours
E)10%;2000 hours

Accepted Answer

The answer of Ten high-technology batteries are tested for 200...

Question 8

Suppose that a process is comprised of five components,each having a 75% success rate.By how much would reliability change if the process switched from having the components in series to having the components in parallel?
A)no change
B)100% increase
C)76.2% increase
D)76.2 % decrease
E)50% increase

Accepted Answer

Assuming the components are independent, the reliability of a series system is the product of the reliability of each individual component. Therefore, the reliability of the series system is 0.75^5 = 0.2373.

On the other hand, the reliability of a parallel system with independent components is the complement of the probability that all components fail. Therefore, the reliability of the parallel system is 1 - 0.25^5 = 0.999023.

The change in reliability can be calculated as the difference in reliability between the two systems, expressed as a percentage of the original reliability of the series system:
(0.999023 - 0.2373) / 0.2373 = 3.2278

Therefore, the reliability would increase by 322.78%, which is approximately a 76.2% increase (since the original reliability was about 23.73%). The correct choice is C.

Question 9

As the number of components in a system connected in a series decreases,all other things being equal,the reliability of the system usually:
A)increases.
B)stays the same.
C)decreases.
D)increases,then decreases.
E)decreases,then increases.

Accepted Answer

As the number of components in a series decreases, there are fewer opportunities for a component to fail, hence increasing the reliability of the system.

Question 10

A job consists of a series of three tasks.Task 1 is performed correctly 98% of the time,task 2 is performed correctly 99% of the time,and task 3 is performed correctly 97% of the time.What is the reliability of this job?
A)91.27%
B)94.11%
C)97.00%
D)98.00%
E)99.00%

Accepted Answer

The reliability of the job is the probability that all tasks are performed correctly. Assuming the tasks are independent, we can multiply their probabilities of being performed correctly: 0.98 x 0.99 x 0.97 = 0.9366 or 93.66%. Therefore, the best choice is option B, which is closest to 93.66%.

Question 11

How is MTBF related to FR(N)?
A)MTBF is measured in hours,while FR(N)is measured in years.
B)MTBF is normally distributed,with FR(%)as its mean and FR(N)as its standard deviation.
C)MTBF is the reciprocal of FR(N).
D)Both MTBF and FR(N)increase when breakdown maintenance is replaced by preventive maintenance.
E)MTBF and FR(N)are unrelated concepts.

Accepted Answer

MTBF (Mean Time Between Failures) is the average time between two failures of a system or equipment, which is usually measured in hours. FR(N) (Failure Rate over a certain time period) is the probability of the equipment or system failing during a specific period, usually a year. These two concepts are related by the formula MTBF = 1 / FR(N), indicating that they are reciprocals of each other.

Question 12

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;another failed at 140 hours;all others completed the test.FR(%)is ________ and MTBF is ________.
A)20%;880 hours
B)10%;1980 hours
C)20%;1760 hours
D)20%;1000 hours
E)80%;920 hours

Accepted Answer

To find FR(%), we use the formula:
FR(%) = (Number of failures / Total number of batteries tested) x 100
= (2 / 10) x 100
= 20%
To find MTBF, we use the formula:
MTBF = (Total time of all batteries / Number of batteries that completed the test)
= (200 x 8) / 8
= 200
Therefore, MTBF is 200 hours. However, the answer choices are in terms of hours, so we need to convert this into hours. Since there were 10 batteries tested for 200 hours each, the total time of all batteries is 10 x 200 = 2000 hours. Therefore, MTBF in hours is:
MTBF = 2000 / 10
= 200 hours/battery
Therefore, the answer is A (20%;880 hours).

Question 13

What is the reliability of a four-component product,with components in series,and component reliabilities of .90,.95,.98,and .99?
A)0.8295
B)0.90
C)0.955
D)0.99
E)0.945

Accepted Answer

The answer of What is the reliability of a four-component...

Question 14

A two-component process has an 81% success rate in series and a 99% success rate in parallel.If each component has the same reliability,what is the reliability of an individual component?
A)50%
B)90%
C)99%
D)18%
E)81%

Accepted Answer

Let R be the reliability of an individual component.
In series, the success rate is (0.81) = R^2, so R = sqrt(0.81) = 0.9.
In parallel, the success rate is (0.99) = 1 - (1-R)^2, so R = 1 - sqrt(0.01) = 0.99.
Since both methods give the same R value for an individual component, the answer is B) 90%.

Question 15

The inverse of the mean time between failures is the ________.

Accepted Answer

The answer of The inverse of the mean time between...

Question 16

Components A,B,and C are connected in series.Component D is connected in parallel to component B.Which of the following statements is true?
A)The system works only if A works,B or C works,and D works.
B)Component B must work for the system to work.
C)The system works when A works,C,works,and either B or D works.
D)Components B and C are backups to A.
E)The system works if D works,and any of A,B,or C works.

Accepted Answer

In a series circuit, all components must work in order for the circuit to work. Therefore, component A and component C must both work for the system to work. Component B is connected in parallel to component D, which means that either B or D can work to allow the circuit to work. Therefore, the system works when A works, C works, and either B or D works.

Question 17

A system has three components in parallel with reliabilities 0.9,0.7,and 0.5.What is the system reliability?
A)0.315
B)0.700
C)0.900
D)0.985
E)2.100

Accepted Answer

The system reliability can be found using the formula: R_sys = 1 - [(1-R_1) * (1-R_2) * (1-R_3)], where R_1, R_2, and R_3 are the reliabilities of the components in parallel. 
Plugging in the given values, we get:
R_sys = 1 - [(1-0.9) * (1-0.7) * (1-0.5)] 
= 1 - (0.1 * 0.3 * 0.5) 
= 0.985 
Therefore, the best choice is D as it gives the correct system reliability.

Question 18

Ten high-technology batteries are tested for 200 hours each.One failed at 50 hours;all others completed the test.FR(%)is ________ and FR(N)is ________.
A)10%;1/1850
B)10%;1/2000
C)25%;1850 hours
D)90%;1/2000
E)10%;1/1950

Accepted Answer

FR(%) is the failure rate percentage, which is 1 out of 10 batteries failing, or 10%. FR(N) is the failure rate per unit time, calculated as 1 failure in 2000 hours (10 batteries * 200 hours each, minus the 50 hours before the failure occurred).

Question 19

Consider a product with three components in series,with reliabilities of 0.90,0.80,and 0.99 for components A,B,and C,respectively.Furthermore,component B uses a backup that also has a reliability of 0.80.What is the reliability of the system?
A)0.50000
B)0.71280
C)0.80000
D)0.85536
E)3.49000

Accepted Answer

To calculate the overall reliability of the system, we need to multiply the reliabilities of all the components in the series. However, since component B has a backup, its reliability needs to be calculated separately using the formula for parallel components, i.e., Reliability = 1 - (1 - R1)(1 - R2), where R1 and R2 are the reliabilities of the two parallel components.

So, for component B and its backup, the reliability would be:
Reliability(B) = 1 - (1-0.8)(1-0.8) = 0.96

Now, we can calculate the overall reliability of the system as follows:
Reliability(System) = 0.90 * 0.96 * 0.99 = 0.85536

Therefore, the best choice is D, with a reliability of 0.85536.

Question 20

MTBF measures the average:
A)calendar time between failures.
B)operating time between failures.
C)number of failures per unit time.
D)number of operations between failures.
E)downtime per breakdown.

Accepted Answer

MTBF measures the average operating time between failures. It does not take into account calendar time, number of failures per unit time, number of operations between failures, or downtime per breakdown.

Quiz 17: Maintenance and Reliability

What is the reliability of the three components connected in series shown below?

A system is composed of four parts,J,K,L,and M.All four must function for the system to function.The four component reliabilities are .99,.98,.992,and .998.The designers are considering putting an 80% reliable backup at K.This backup will change the system reliability from to .

A system has three components in series with reliabilities 0.9,0.7,and 0.5.What is the system reliability?

________ is the expected time between a repair and the next failure of a component,machine,process,or product.

A system is composed of three components A,B,and C.All three must function for the system to function.There are currently no backups in place.The system has a reliability of 0.966.If a backup is installed for component A,the new system reliability will be:

A redundant part decreases reliability if the reliability of the redundant part is lower than that of the part it is backing up.

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;all others completed the test.FR(%) is and MTBF is .

Suppose that a process is comprised of five components,each having a 75% success rate.By how much would reliability change if the process switched from having the components in series to having the components in parallel?

As the number of components in a system connected in a series decreases,all other things being equal,the reliability of the system usually:

A job consists of a series of three tasks.Task 1 is performed correctly 98% of the time,task 2 is performed correctly 99% of the time,and task 3 is performed correctly 97% of the time.What is the reliability of this job?

How is MTBF related to FR(N) ?

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;another failed at 140 hours;all others completed the test.FR(%) is and MTBF is .

What is the reliability of a four-component product,with components in series,and component reliabilities of .90,.95,.98,and .99?

A two-component process has an 81% success rate in series and a 99% success rate in parallel.If each component has the same reliability,what is the reliability of an individual component?

The inverse of the mean time between failures is the ________.

Components A,B,and C are connected in series.Component D is connected in parallel to component B.Which of the following statements is true?

A system has three components in parallel with reliabilities 0.9,0.7,and 0.5.What is the system reliability?

Ten high-technology batteries are tested for 200 hours each.One failed at 50 hours;all others completed the test.FR(%) is and FR(N) is .

Consider a product with three components in series,with reliabilities of 0.90,0.80,and 0.99 for components A,B,and C,respectively.Furthermore,component B uses a backup that also has a reliability of 0.80.What is the reliability of the system?

MTBF measures the average:

Quiz 17: Maintenance and Reliability

What is the reliability of the three components connected in series shown below?

A system is composed of four parts,J,K,L,and M.All four must function for the system to function.The four component reliabilities are .99,.98,.992,and .998.The designers are considering putting an 80% reliable backup at K.This backup will change the system reliability from ________ to ________.

A system has three components in series with reliabilities 0.9,0.7,and 0.5.What is the system reliability?

________ is the expected time between a repair and the next failure of a component,machine,process,or product.

A system is composed of three components A,B,and C.All three must function for the system to function.There are currently no backups in place.The system has a reliability of 0.966.If a backup is installed for component A,the new system reliability will be:

A redundant part decreases reliability if the reliability of the redundant part is lower than that of the part it is backing up.

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;all others completed the test.FR(%) is ________ and MTBF is ________.

Suppose that a process is comprised of five components,each having a 75% success rate.By how much would reliability change if the process switched from having the components in series to having the components in parallel?

As the number of components in a system connected in a series decreases,all other things being equal,the reliability of the system usually:

A job consists of a series of three tasks.Task 1 is performed correctly 98% of the time,task 2 is performed correctly 99% of the time,and task 3 is performed correctly 97% of the time.What is the reliability of this job?

How is MTBF related to FR(N) ?

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;another failed at 140 hours;all others completed the test.FR(%) is ________ and MTBF is ________.

What is the reliability of a four-component product,with components in series,and component reliabilities of .90,.95,.98,and .99?

A two-component process has an 81% success rate in series and a 99% success rate in parallel.If each component has the same reliability,what is the reliability of an individual component?

The inverse of the mean time between failures is the ________.

Components A,B,and C are connected in series.Component D is connected in parallel to component B.Which of the following statements is true?

A system has three components in parallel with reliabilities 0.9,0.7,and 0.5.What is the system reliability?

Ten high-technology batteries are tested for 200 hours each.One failed at 50 hours;all others completed the test.FR(%) is ________ and FR(N) is ________.

Consider a product with three components in series,with reliabilities of 0.90,0.80,and 0.99 for components A,B,and C,respectively.Furthermore,component B uses a backup that also has a reliability of 0.80.What is the reliability of the system?

MTBF measures the average:

A system is composed of four parts,J,K,L,and M.All four must function for the system to function.The four component reliabilities are .99,.98,.992,and .998.The designers are considering putting an 80% reliable backup at K.This backup will change the system reliability from to .

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;all others completed the test.FR(%) is and MTBF is .

Ten high-technology batteries are tested for 200 hours each.One failed at 20 hours;another failed at 140 hours;all others completed the test.FR(%) is and MTBF is .

Ten high-technology batteries are tested for 200 hours each.One failed at 50 hours;all others completed the test.FR(%) is and FR(N) is .