University of Phoenix - QNT 275QNT275
week 3 quiz
Your answers : 10/10 (100%)
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Correct answerquestion1
A continuous random variable is a random variable that can:
o
have no random sample
o
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assume no continuous random frequency
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assume any value in one or more intervals
o
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assume only a countable set of values
Correct answerquestion2
To use an F distribution, the random variable must be:
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a discrete random variable
o
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a qualitative random variable
o
a continuous random variable
o
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either a discrete or a continuous random variable
Correct answerquestion3
Which of the following is not a characteristic of the normal distribution?
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The total area under the curve is 1.0
o
The curve is symmetric about the mean
o
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The two tails of the curve extend indefinitely
o
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The value of the mean is always greater than the value of the standard deviation
Correct answerquestion4
The population distribution is the probability distribution of the:
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population probabilities
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whole population of a country
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population data
o
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population means
Correct answerquestion5
The sampling error is:
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an error that occurs when a sample of 30 or more members is drawn
o
the difference between the value of a sample statistic and the value of the corresponding
population parameter
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an error that occurs during collection, recording, and tabulation of data
o
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an error that occurs when a sample of fewer than 30 members is drawn
Correct answerquestion6
The units of an F distribution:
o
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can be negative, zero, or positive
o
are always nonnegative
o
are always negative
o
are always positive
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Correct answerquestion1
You work in marketing for a company that produces work boots. Quality control has sent you a memo
detailing the length of time before the boots wear out under heavy use. They find that the boots wear
out in an average of 208 days, but the exact amount of time varies, following a normal distribution
with a standard deviation of 14 days. For an upcoming ad campaign, you need to know the percent of
the pairs that last longer than six months-that is, 180 days. Use the empirical rule to approximate this
percent.
o
95%
o
2.5%
◦
97.5%
o
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5%
Correct answerquestion2
Which of the following can be represented by a discrete random variable?
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The number of obtained spots when rolling a six-sided die
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The average outside temperature taken every day for two weeks
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The finishing time of participants in a cross-country meet
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The height of college students
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Correct answerquestion3
What does it mean when we say that the tails of the normal curve are asymptotic to the x axis?
o
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The tails gets closer and closer to the x axis and eventually touch it.
o
The tails get closer and closer to the x axis but never touch it.
o
The tails get closer and closer to the x axis and eventually cross this axis.
o
The tails get closer and closer to the x axis and eventually become this axis.
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Incorrect answerquestion4
Which of the following is correct?
o
A continuous random variable has a probability density function but not a cumulative
distribution function.
o
A discrete random variable has a probability mass function but not a cumulative distribution
function.
o
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A continuous random variable has a probability density function, and a discrete random
variable has a probability mass function.
o
A continuous random variable has a probability mass function, and a discrete random
variable has a probability density function.
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Correct answerquestion5
What is probability?
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A value between 0 and 1 assigned to an event that measures the unlikelihood of its
occurrence.
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A numerical value assigned to an event that measures the number of its occurrences.
o
Any value between 0 and 1 is always treated as a probability of an event.
o
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A value between 0 and 1 assigned to an event that measures the likelihood of its occurrence.
Correct answerquestion6
For any normally distributed random variable with mean μ and standard deviation σ, the percent of
the observations that fall between
and
is closest to _______.
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32%
o
95%
o
16% Answers available here http://bit.ly/2Ty7Wu7
o
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68%
Correct answerquestion7
The probability that a normal random variable is less than its mean is ____.
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Cannot be determined
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1.0
o
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0.5
o
0.0
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Correct answerquestion8
Mutually exclusive and collectively exhaustive events _______________.
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do not have to contain all outcomes in a sample space but do not share common outcomes
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contain all outcomes in a sample space and do not share common outcomes.
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do not have to contain all outcomes in a sample space and may share common outcomes
o
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contain all outcomes in a sample space and may share common outcomes
Incorrect answerquestion9
A continuous random variable has the uniform distribution on the interval [a, b] if its probability density
function f(x) ___________.
o
is constant for all x between a and b, and 0 otherwise
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asymptotically approaches the x axis when x increases to +∞ or decreases to -∞
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is symmetric around its mean
o
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is bell-shaped between a and b
Incorrect answerquestion10
Which of the following can be represented by a continuous random variable?
o
The score of a randomly selected student on a five-question multiple-choice quiz
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The number of arrivals to a drive-thru bank window in a four-hour period
o
The time of a flight between Chicago and New York
o
The number of defective light bulbs in a sample of 5
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