Quiz
2
Please put your answers in the following table.
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6 |
7 |
8 |
9 |
10 |
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1. Six
samples of the length of a beam are (2.1, 2.2, 2.0, 1.9, 2.0, 2.1) m, what is
the average length?
A)
2.0
m
B)
1.9
m
C)
2.1
m
D)
2.05
m
2. In
problem 1, what is the standard deviation of the beam length?
A)
0.0 m
B)
0.105 m
C)
0.2 m
D)
Cannot determine
3. In
problem 1, what is the median of the beam length?
A)
2.0
m
B)
1.9
m
C)
2.1
m
D)
2.05
m
4.
A
standard deviation indicates the dispersion of a random variable. (True or
False)
5.
The
CDF of a random variable at positive infinity is 1.0. (True or False)
6.
A
crate is subject to two independently and normally distributed random forces 
and 
. The
two forces act in the opposite directions as shown, the mean and standard
deviation of the resultant force are
F2 F1
A)
220 N and 10 N, respectively.
B)
220 N and 7 N, respectively.
C)
20 N and 14 N, respectively.
D)
20 N and 10 N, respectively.
7.
In
problem 6, the distribution of the resultant force cannot be determined. (True
or False)
8.
In
problem 6, if the two forces act in the same direction, which statement is true
for the resultant force?
A)
and
will remain the same.
B)
will
change, and will not.
C)
and
will both change.
D)
Cannot be determined.
9.
The
strength and stress of a component are independently distributed with normal
distributions 
and 
, respectively. The
reliability of the component is defined by the probability 
. The reliability of the component is
A) 
B) 
C) 1-
D) 0
10. In
problem 9, keeping stress 
constant but
changing strength to 
will improve reliability.
(True or False)