# 10.2 Review questions

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Copy of Review Questions module m17021 (http://cnx.org/content/ m17021/) from Collaborative Statistics by Dean and Illowsky http://cnx.org/content/col10522/ , 12/18/2008 . The FORMAT only of the question numbering has been changed.

The next three questions refer to the following information:

In a survey at Kirkwood Ski Resort the following information was recorded:

 0 – 10 11 - 20 21 - 40 40+ Ski 10 12 30 8 Snowboard 6 17 12 5

Suppose that one person from of the above was randomly selected.

Find the probability that the person was a skier or was age 11 – 20.

REVIEW QUESTION 1 Solution : $\frac{\text{77}}{\text{100}}$

Find the probability that the person was a snowboarder given he/she was age 21 – 40.

REVIEW QUESTION 2 Solution : $\frac{\text{12}}{\text{42}}$

Explain which of the following are true and which are false.

• ## A

Sport and Age are independent events.
• ## B

Ski and age 11 – 20 are mutually exclusive events.
• ## C

$P\left(\text{Ski}\phantom{\rule{2pt}{0ex}}\text{and}\phantom{\rule{2pt}{0ex}}\text{age}\phantom{\rule{2pt}{0ex}}\text{21}-\text{40}\right)
• ## D

$P\left(\text{Snowboard}\phantom{\rule{2pt}{0ex}}\text{or}\phantom{\rule{2pt}{0ex}}\text{age}\phantom{\rule{2pt}{0ex}}0-\text{10}\right)

False

False

True
• ## D

False

The average length of time a person with a broken leg wears a cast is approximately 6 weeks. The standard deviation is about 3 weeks. Thirty people who had recently healed from broken legs were interviewed. State the distribution that most accurately reflects total time to heal for the thirty people.

REVIEW QUESTION 4 Solution : $N\left(\text{180},\text{16}\text{.}\text{43}\right)$

The distribution for $X$ is Uniform. What can we say for certain about the distribution for $\overline{X}$ when $n=1$ ?

• ## A

The distribution for $\overline{X}$ is still Uniform with the same mean and standard dev. as the distribution for $X$ .
• ## B

The distribution for $\overline{X}$ is Normal with the different mean and a different standard deviation as the distribution for $X$ .
• ## C

The distribution for $\overline{X}$ is Normal with the same mean but a larger standard deviation than the distribution for $X$ .
• ## D

The distribution for $\overline{X}$ is Normal with the same mean but a smaller standard deviation than the distribution for $X$ .

REVIEW QUESTION 5 Solution : A

The distribution for $X$ is uniform. What can we say for certain about the distribution for $\sum X$ when $n=50$ ?

• ## A

The distribution for $\sum X$ is still uniform with the same mean and standard deviation as the distribution for $X$ .
• ## B

The distribution for $\sum X$ is Normal with the same mean but a larger standard deviation as the distribution for $X$ .
• ## C

The distribution for $\sum X$ is Normal with a larger mean and a larger standard deviation than the distribution for $X$ .
• ## D

The distribution for $\sum X$ is Normal with the same mean but a smaller standard deviation than the distribution for $X$ .

REVIEW QUESTION 6 Solution : C

The next three questions refer to the following information:

A group of students measured the lengths of all the carrots in a five-pound bag of baby carrots. They calculated the average length of baby carrots to be 2.0 inches with a standard deviation of 0.25 inches. Suppose we randomly survey 16 five-pound bags of baby carrots.

State the approximate distribution for $\overline{X}$ , the distribution for the average lengths of baby carrots in 16 five-pound bags. $\overline{X}\text{~}$

REVIEW QUESTION 7 Solution : $N\left(2\text{,}\frac{\text{.25}}{\sqrt{\text{16}}}\right)$

Explain why we cannot find the probability that one individual randomly chosen carrot is greater than 2.25 inches.

## Review question 8 solution

We do not know the probability distribution for the underlying population of lengths of the individual carrots.

Find the probability that $\overline{X}$ is between 2 and 2.25 inches.

REVIEW QUESTION 9 Solution : 0.5000

The next three questions refer to the following information:

At the beginning of the term, the amount of time a student waits in line at the campus store is normally distributed with a mean of 5 minutes and a standard deviation of 2 minutes.

Find the 90th percentile of waiting time in minutes.

REVIEW QUESTION 10 Solution : 7.6

Find the median waiting time for one student.

REVIEW QUESTION 11 Solution : 5

Find the probability that the average waiting time for 40 students is at least 4.5 minutes.

REVIEW QUESTION 12 Solution : 0.9431

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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