# QNT 275 Week 3 Quiz

**QNT/275**

**STATISTICS FOR DECISION MAKING**

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**Week 3 Quiz**·

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question

**1**

What does it mean when we say that the tails of the

normal curve are asymptotic to the

*x*axis?

o

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 and

eventually cross this axis.

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 become this axis.

question

**2**

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%

o

97.5%

o

5%

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question

**3**

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 _______.

****

o

95%

o

16%

o

68%

o

32%

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question

**4**

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

o

is bell-shaped between a and b

o

is symmetric

around its mean

o

asymptotically approaches the x axis when x increases to

+∞ or decreases to -∞

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question

**5**

Mutually exclusive and collectively

exhaustive events _______________.

o

do not have to contain all outcomes in a sample space and

may share common outcomes

o

contain all

outcomes in a sample space and do not share common outcomes.

o

contain all outcomes in a sample space and may share

common outcomes

o

do not have to contain all outcomes in a sample space but

do not share common outcomes

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question

**6**

What is probability?

o

Any value between 0 and 1 is always treated as a

probability of an event.

o

A value between 0

and 1 assigned to an event that measures the likelihood of its occurrence.

o

A value between 0 and 1 assigned to an event that

measures the unlikelihood of its occurrence.

o

A numerical value assigned to an event that measures the

number of its occurrences.

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·

question

**7**

Which of the following can be represented by a continuous

random variable?

o

The number of arrivals to a drive-thru bank window in a

four-hour period

o

The number of defective light bulbs in a sample of 5

o

The score of a randomly selected student on a

five-question multiple-choice quiz

o

The time of a

flight between Chicago and New York

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·

question

**8**

Which of the following is correct?

o

A continuous random variable has a probability density

function but not a cumulative distribution function.

o

A continuous

random variable has a probability density function, and a discrete random

variable has a probability mass function.

o

A discrete random variable has a probability mass

function but not a cumulative distribution 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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question

**9**

Which of the following can be represented by a discrete

random variable?

o

The finishing time of participants in a cross-country

meet

o

The number of

obtained spots when rolling a six-sided die

o

The average outside temperature taken every day for two

weeks

o

The height of college students

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question

**10**

The probability that a normal random variable is less

than its mean is ____.

o

Cannot be determined

o

0.0

o

1.0

o

0.5

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