Question 1

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

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

Question 2

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 find the reliability of the system, we need to multiply the reliability of each component and its backup (if any). So, the reliability of the system is:

Reliability of A x Reliability of B (with backup) x Reliability of C
= 0.9 x (0.8 + (0.2 x 0.8)) x 0.99
= 0.9 x 0.96 x 0.99
= 0.85536

Therefore, the reliability of the system is 0.85536, which is closest to option D (0.85536).

Question 3

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 operating time between failures, not calendar time or the number of failures per unit time. It also does not measure the number of operations between failures or the downtime per breakdown.

Question 4

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

We can use the formula for series reliability:
R_total = R_1 x R_2 x R_3
where R_1, R_2, and R_3 are the reliabilities of each task.

Plugging in the given values:
R_total = 0.98 x 0.99 x 0.97 = 0.9411

Converting to percentage:
R_total = 94.11%

Therefore, the reliability of the job is 94.11%. The best choice is option B.

Question 5

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 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 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

The Failure rate in percentage (FR(%)) is calculated as the number of failures divided by the total number of batteries tested multiplied by 100. In this case, there was only one failure out of ten batteries, so the FR(%) is (1/10) x 100 = 10%.

The Failure rate in Number (FR(N)) is calculated as the total number of failures divided by the total number of hours of testing for all the batteries. In this case, there was only one failure at 50 hours, and the total number of batteries tested for 200 hours each is 10, so the total number of hours of testing is 10 x 200 = 2000 hours. Therefore, the FR(N) is 1/2000.

Thus, the best choice is A) 10%; 1/1850, as none of the other options match the correct values for FR(%), FR(N), or both.

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

If the five components are in series, then the probability of the process succeeding is (0.75)^5 = 0.2373.

If the five components are in parallel, then the probability of the process succeeding is 1 - (0.25)^5 = 0.9937.

The reliability in the parallel case is much higher than in the series case.

The increase in reliability is (0.9937 - 0.2373)/0.2373 = 3.16 or 316%.

But since the question asks for how much the reliability has changed, we must subtract 1 from the increase percentage to get the answer: 3.16 - 1 = 2.16 or 216%, which is approximately a 76.2% increase (since 1 + 0.762 = 1.762 or 176.2%). Therefore, the answer is C.

Question 9

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

In a series system, the reliability is the product of the reliabilities of the components. Let the reliability of each component be x. Then, x^2 = 0.81, so x = 0.9. In a parallel system, the reliability is 1 - (1-x)^2 = 0.99, which also confirms x = 0.9.

Question 10

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

Accepted Answer

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

Question 11

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

When components are connected in series, the failure of any one component can cause the entire system to fail. Therefore, as the number of components in a series decreases, the system becomes less vulnerable to component failures and thus more reliable.

Question 12

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 can be found by multiplying the reliabilities of all the components in series. 
System reliability = 0.9 x 0.7 x 0.5 = 0.315. 
Therefore, the best choice is A.

Question 13

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

To find the new system reliability with the backup at K, we need to use the formula for parallel system reliability which is:
Rs = 1 - [(1-Ra) x (1-Rb)]
where Rs is the system reliability, Ra and Rb are the reliabilities of two parallel components.
If we add the 80% backup at K, its reliability becomes 0.8. Thus, the new reliabilities of the system components become:
J: 0.99
K: 0.98 x 0.8 + (1 - 0.8) = 0.984
L: 0.992
M: 0.998
Now applying the above formula, we get:
Rs = 1 - [(1-0.99) x (1-0.984) x (1-0.992) x (1-0.998)]
Rs = 0.9762 
Therefore, the new system reliability is 0.9762 or approximately 0.976. The initial system reliability was 0.9605. Thus, the answer is B, which shows the change in system reliability from 0.9605 to 0.9762.

Question 14

________ 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 15

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 16

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 consecutive failures of a system or a component, measured in hours. FR(N) (Failure Rate per Unit Time) is the probability of failure of a system or a component per unit time, measured in 1/year or 1/hour. The relationship between the two is that MTBF is the reciprocal of FR(N), which means MTBF = 1/FR(N).

Question 17

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, the current flows through each component in sequence, so for the circuit to work, all the components must work. Therefore, A and C both have to work, but component B can be substituted by component D since it is connected in parallel. This means that as long as either B or D works, the circuit will still work. Hence, the system works when A works, C works, and either B or D works.

Question 18

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 is given by the formula:
R(sys) = 1 - (1-R1)(1-R2)(1-R3)
where R1,R2 and R3 are the reliabilities of the three components.
Substituting the given values, we get:
R(sys) = 1 - (1-0.9)(1-0.7)(1-0.5)
R(sys) = 1 - 0.1*0.3*0.5
R(sys) = 0.985
Therefore, the best choice is D.

Question 19

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

Installing a backup for component A will increase the reliability of the system since there will be a backup in case A fails. Therefore, the new system reliability will be greater than 0.966. There is no information given about the effect of installing a backup for component B, so it cannot be determined whether the system reliability will be greater or less than it would be with a backup for A only. Therefore, options C and E can be eliminated. Finally, since the system reliability is currently 0.966 and installing a backup for component A will improve the reliability, it is clear that the new system reliability will be greater than the current reliability. Therefore, option D is the best choice.

Question 20

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 reliability of a series system is the product of the reliabilities of its components. Therefore, the reliability is 0.90 * 0.95 * 0.98 * 0.99 = 0.8295.

Quiz 17: Maintenance and Reliability

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 .

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 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?

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 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 50 hours;all others completed the test.FR(%) is and FR(N) 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?

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 ________.

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

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 .

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

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

How is MTBF related to FR(N) ?

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?

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:

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

Quiz 17: Maintenance and Reliability

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 ________.

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 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?

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 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 50 hours;all others completed the test.FR(%) is ________ and FR(N) 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?

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 ________.

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

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 ________.

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

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

How is MTBF related to FR(N) ?

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?

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:

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

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 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 50 hours;all others completed the test.FR(%) is and FR(N) is .

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 .