Quiz
3
Please put your answers in the following table.
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5 |
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9 |
10 |
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1. A component
is subjected to two independent forces 
and
, and the resultant force is given by 
where 
kN and 
kN. What is the mean value
of 
?
A.
80 kN
B.
20 kN
C.
-20 kN
D.
40 kN
2.
In
problem 1, what is the standard deviation of 
?
A.
5 kN
B.
7 kN
C.
1 kN
D.
Cannot be determined
3.
In
problem 1, the failure event is defined by 
. What is the probability
of failure?
B.
C.
D.
4.
In
problem 1, what is the probability that Y
is less than 20 kN?
A.
< 50%
B.
> 50%
C.
= 50%
D.
Cannot be determined
5.
For
a beam, the factor of safety is defined by 
, where 
and 
are the means of the stress 
and strength of the beam, respectively. The reliability of
the beam is defined by the probability 
. Also denote 
and 
as the standard deviations of and , respectively.
Which of the following actions cannot improve reliability?
- Increase
and keep and constant - Keep constant and increase
- Keep constant and decrease
- Keep constant and decrease both and .
6.
In
problem 5, the factor of safety has no relation with the reliability of the beam.
(True or False)
7.
100
failure samples are obtained out of 1,000,000 samples. The probability of
failure estimated is
A.
0.9999 B. 0.0001 C. 0.5 D. 0
8.
In
problem 7, if 1000 failure samples are obtained, the reliability will be decreased.
(True or False)
9.
If
the forces acting one a component follow independent normal distributions, the
resultant force also follows a normal distribution. (True or False)
10. A design team designed two
cantilever beams. The deflection of the tip of each beam is normally distributed as shown. If a smaller deflection is
preferred, which design is better?
A. Design 1 B. Design 2
C. Equally good D.
Cannot determine
