# 8.14 Confidence intervals: review

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The next three problems refer to the following situation: Suppose that a sample of 15 randomly chosen people were put on a special weight loss diet. The amount of weight lost, in pounds, follows an unknown distribution with mean equal to 12 pounds and standard deviation equal to 3 pounds. Assume that the distribution for the weight loss is normal.

To find the probability that the mean amount of weight lost by 15 people is no more than 14 pounds, the random variable should be:

• The number of people who lost weight on the special weight loss diet
• The number of people who were on the diet
• The mean amount of weight lost by 15 people on the special weight loss diet
• The total amount of weight lost by 15 people on the special weight loss diet

C

Find the probability asked for in the previous problem.

0.9951

Find the 90th percentile for the mean amount of weight lost by 15 people.

12.99

The next three questions refer to the following situation: The time of occurrence of the first accident during rush-hour traffic at a major intersection is uniformly distributed between the three hour interval 4 p.m. to 7 p.m. Let $X$ = the amount of time (hours) it takes for the first accident to occur.

• So, if an accident occurs at 4 p.m., the amount of time, in hours, it took for the accident to occur is _______.
• $\mu =$ _______
• ${\sigma }^{2}=$ _______

What is the probability that the time of occurrence is within the first half-hour or the last hour of the period from 4 to 7 p.m.?

• Cannot be determined from the information given
• $\frac{1}{6}$
• $\frac{1}{2}$
• $\frac{1}{3}$

C

The 20th percentile occurs after how many hours?

• 0.20
• 0.60
• 0.50
• 1

B

Assume Ramon has kept track of the times for the first accidents to occur for 40 different days. Let $C$ = the total cumulative time. Then $C$ follows which distribution?

• $U\left(0,3\right)$
• $N\left(\text{60},\text{5.477}\right)$
• $N\left(1\text{.}5,0\text{.}\text{01875}\right)$

C

Using the information in question #6, find the probability that the total time for all first accidents to occur is more than 43 hours.

0.9990

The next two questions refer to the following situation: The length of time a parent must wait for his children to clean their rooms is uniformly distributed in the time interval from 1 to 15 days.

How long must a parent expect to wait for his children to clean their rooms?

• 8 days
• 3 days
• 14 days
• 6 days

A

What is the probability that a parent will wait more than 6 days given that the parent has already waited more than 3 days?

• 0.5174
• 0.0174
• 0.7500
• 0.2143

C

The next five problems refer to the following study: Twenty percent of the students at a local community college live in within five miles of the campus. Thirty percent of the students at the same community college receive some kind of financial aid. Of those who live within five miles of the campus, 75% receive some kind of financial aid.

Find the probability that a randomly chosen student at the local community college does not live within five miles of the campus.

• 80%
• 20%
• 30%
• Cannot be determined

A

Find the probability that a randomly chosen student at the local community college lives within five miles of the campus or receives some kind of financial aid.

• 50%
• 35%
• 27.5%
• 75%

B

Based upon the above information, are living in student housing within five miles of the campus and receiving some kind of financial aid mutually exclusive?

• Yes
• No
• Cannot be determined

B

The interest rate charged on the financial aid is _______ data.

• quantitative discrete
• quantitative continuous
• qualitative discrete
• qualitative

B

What follows is information about the students who receive financial aid at the local community college.

• 1st quartile = $250 • 2nd quartile =$700
• 3rd quartile = $1200 (These amounts are for the school year.) If a sample of 200 students is taken, how many are expected to receive$250 or more?

• 50
• 250
• 150
• Cannot be determined

• 150

The next two problems refer to the following information: $P\left(A\right)=0\text{.}2$ , $P\left(B\right)=0\text{.}3$ , $A$ and $B$ are independent events.

$P\left(A\phantom{\rule{2pt}{0ex}}\text{AND}\phantom{\rule{2pt}{0ex}}B\right)=$

• 0.5
• 0.6
• 0
• 0.06

D

$P\left(A\phantom{\rule{2pt}{0ex}}\text{OR}\phantom{\rule{2pt}{0ex}}B\right)=$

• 0.56
• 0.5
• 0.44
• 1

C

If $H$ and $D$ are mutually exclusive events,  $P\left(H\right)=0\text{.}\text{25}$ , $P\left(D\right)=0\text{.}\text{15}$ , then $P\left(H|D\right)$

• 1
• 0
• 0.40
• 0.0375

B

where we get a research paper on Nano chemistry....?
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
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
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