# 8.9 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?

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

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

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?
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
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
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
how did you get the value of 2000N.What calculations are needed to arrive at it
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1 It is estimated that 30% of all drivers have some kind of medical aid in South Africa. What is the probability that in a sample of 10 drivers: 3.1.1 Exactly 4 will have a medical aid. (8) 3.1.2 At least 2 will have a medical aid. (8) 3.1.3 More than 9 will have a medical aid.