# 8.1 Homework

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If you are using a student's-t distribution for a homework problem below, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)

Among various ethnic groups, the standard deviation of heights is known to be approximately 3 inches. We wish to construct a 95% confidence interval for the mean height of male Swedes. 48 male Swedes are surveyed. The sample mean is 71 inches. The sample standard deviation is 2.8 inches.

• $\overline{x}=$ $\text{________}$
• $\sigma =$ $\text{________}$
• ${s}_{x}=$ $\text{________}$
• $n=$ $\text{________}$
• $n-1=$ $\text{________}$
• Define the Random Variables $X$ and $\overline{X}$ , in words.
• Which distribution should you use for this problem? Explain your choice.
• Construct a 95% confidence interval for the population mean height of male Swedes.
• State the confidence interval.
• Sketch the graph.
• Calculate the error bound.
• What will happen to the level of confidence obtained if 1000 male Swedes are surveyed instead of 48? Why?

• 71
• 3
• 2.8
• 48
• 47
• $N$ $\left(\text{71},\frac{3}{\sqrt{\text{48}}}\right)$
• CI: (70.15,71.85)
• EB = 0.85

In six packages of “The Flintstones® Real Fruit Snacks” there were 5 Bam-Bam snack pieces. The total number of snack pieces in the six bags was 68. We wish to calculate a 96% confidence interval for the population proportion of Bam-Bam snack pieces.

• Define the Random Variables $X$ and $P\text{'}$ , in words.
• Which distribution should you use for this problem? Explain your choice
• Calculate $p\text{'}$ .
• Construct a 96% confidence interval for the population proportion of Bam-Bam snack pieces per bag.
• State the confidence interval.
• Sketch the graph.
• Calculate the error bound.
• Do you think that six packages of fruit snacks yield enough data to give accurate results? Why or why not?

A random survey of enrollment at 35 community colleges across the United States yielded the following figures (source: Microsoft Bookshelf ): 6414; 1550; 2109; 9350; 21828; 4300; 5944; 5722; 2825; 2044; 5481; 5200; 5853; 2750; 10012; 6357; 27000; 9414; 7681; 3200; 17500; 9200; 7380; 18314; 6557; 13713; 17768; 7493; 2771; 2861; 1263; 7285; 28165; 5080; 11622. Assume the underlying population is normal.

• $\overline{x}=$
• ${s}_{x}=$ $\text{________}$
• $n=$ $\text{________}$
• $n-1=$ $\text{________}$
• Define the Random Variables $X$ and $\overline{X}$ , in words.
• Which distribution should you use for this problem? Explain your choice.
• Construct a 95% confidence interval for the population mean enrollment at community colleges in the United States.
• State the confidence interval.
• Sketch the graph.
• Calculate the error bound.
• What will happen to the error bound and confidence interval if 500 community colleges were surveyed? Why?

• 8629
• 6944
• 35
• 34
• ${t}_{\text{34}}$
• CI: (6244, 11,014)
• EB = 2385
• It will become smaller

From a stack of IEEE Spectrum magazines, announcements for 84 upcoming engineering conferences were randomly picked. The mean length of the conferences was 3.94 days, with a standard deviation of 1.28 days. Assume the underlying population is normal.

• Define the Random Variables $X$ and $\overline{X}$ , in words.
• Which distribution should you use for this problem? Explain your choice.
• Construct a 95% confidence interval for the population mean length of engineering conferences.
• State the confidence interval.
• Sketch the graph.
• Calculate the error bound.

#### Questions & Answers

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
characteristics of micro business
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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