QNT 275 Week 3 Quiz

Complete the quiz for Week 3

• question1

What does it mean when we say that the tails of the normal curve are asymptotic to the x axis?

The tails gets closer and closer to the x axis and eventually touch it.

The tails get closer and closer to the x axis and eventually cross this axis.

The tails get closer and closer to the x axis but never touch it.

The tails get closer and closer to the x axis and eventually become this axis.

question2

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.

95%

2.5%

97.5%

5%

• question3

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 _______. 

95%

16%

68%

32%

• question4

A continuous random variable has the uniform distribution on the interval [a, b] if its probability density functionf(x) ___________.

is constant for all x between a and b, and 0 otherwise

is bell-shaped between a and b

is symmetric around its mean

asymptotically approaches the x axis when x increases to +∞ or decreases to -∞

• question5

Mutually exclusive and collectively exhaustive events _______________.

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

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

contain all outcomes in a sample space and may share common outcomes

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

• question6

What is probability?

Any value between 0 and 1 is always treated as a probability of an event.

A value between 0 and 1 assigned to an event that measures the likelihood of its occurrence.

A value between 0 and 1 assigned to an event that measures the unlikelihood of its occurrence.

A numerical value assigned to an event that measures the number of its occurrences.

• question7

Which of the following can be represented by a continuous random variable?

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

The number of defective light bulbs in a sample of 5

The score of a randomly selected student on a five-question multiple-choice quiz

The time of a flight between Chicago and New York

• question8

Which of the following is correct?

A continuous random variable has a probability density function but not a cumulative distribution function.

A continuous random variable has a probability density function, and a discrete random variable has a probability mass function.

A discrete random variable has a probability mass function but not a cumulative distribution function.

A continuous random variable has a probability mass function, and a discrete random variable has a probability density function.

• question9

Which of the following can be represented by a discrete random variable?

The finishing time of participants in a cross-country meet

The number of obtained spots when rolling a six-sided die

The average outside temperature taken every day for two weeks

The height of college students

• question10

The probability that a normal random variable is less than its mean is ____.

Cannot be determined

0.0

1.0

0.5