**QNT 275 WEEK 3 QUIZ**

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

0.5

Cannot be determined

1.0

0.0

**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

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

is bell-shaped between a and b

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

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

is symmetric around its mean

**What is probability? **

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

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 unlikelihood of its occurrence.

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

**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%

32%

68%

16%

**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 time of a flight between Chicago and New York

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

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

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.

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

**Which of the following is correct?**

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

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.

# QNT 275 WEEK 3 QUIZ

**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.**

2.5%

5%

97.5%

95%

# QNT 275 WEEK 3 QUIZ

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

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

The height of college students

The finishing time of participants in a cross-country meet

The average outside temperature taken every day for two weeks

# QNT 275 WEEK 3 QUIZ

** **

**QNT 275 WEEK 3 QUIZ**

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

0.5

Cannot be determined

1.0

0.0

**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

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

is bell-shaped between a and b

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

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

is symmetric around its mean

**What is probability? **

# QNT 275 WEEK 3 QUIZ

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

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 unlikelihood of its occurrence.

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

**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%

32%

68%

16%

# QNT 275 WEEK 3 QUIZ

**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 time of a flight between Chicago and New York

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

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

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.

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

**Which of the following is correct?**

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

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.

**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.**

2.5%

5%

97.5%

95%

# QNT 275 WEEK 3 QUIZ

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

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

The height of college students

The finishing time of participants in a cross-country meet

The average outside temperature taken every day for two weeks