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This module provides a number of homework/review exercises summarizing topics related to Discrete Random Variables.

A sociologist wants to know the opinions of employed adult women about government funding for day care. She obtains a list of 520 members of a local business and professional women’s club and mails a questionnaire to 100 of these women selected at random. 68 questionnaires are returned. What is the population in this study?

  • All employed adult women
  • All the members of a local business and professional women’s club
  • The 100 women who received the questionnaire
  • All employed women with children


The next two questions refer to the following: An article from The San Jose Mercury News was concerned with the racial mix of the 1500 students at Prospect High School in Saratoga, CA. The table summarizes the results. (Male and female values are approximate.)

Ethnic Group
Gender White Asian Hispanic Black American Indian
Male 400 168 115 35 16
Female 440 132 140 40 14

Find the probability that a student is Asian or Male.


Find the probability that a student is Black given that the student is Female.


A sample of pounds lost, in a certain month, by individual members of a weight reducing clinic produced the following statistics:

  • Mean = 5 lbs.
  • Median = 4.5 lbs.
  • Mode = 4 lbs.
  • Standard deviation = 3.8 lbs.
  • First quartile = 2 lbs.
  • Third quartile = 8.5 lbs.

The correct statement is:

  • One fourth of the members lost exactly 2 pounds.
  • The middle fifty percent of the members lost from 2 to 8.5 lbs.
  • Most people lost 3.5 to 4.5 lbs.
  • All of the choices above are correct.


What does it mean when a data set has a standard deviation equal to zero?

  • All values of the data appear with the same frequency.
  • The mean of the data is also zero.
  • All of the data have the same value.
  • There are no data to begin with.


The statement that best describes the illustration below is:

Horizontal boxplot starting with a dashed line and ending with one whisker on the right.

  • The mean is equal to the median.
  • There is no first quartile.
  • The lowest data value is the median.
  • The median equals ( Q1 + Q3 ) 2 size 12{ { { size 8{ \( Q1+Q3 \) } } over { size 8{2} } } } {}


A “friend” offers you the following “deal.” For a $10 fee, you may pick an envelope from a box containing 100 seemingly identical envelopes. However, each envelope contains a coupon for a free gift.

  • 10 of the coupons are for a free gift worth $6.
  • 80 of the coupons are for a free gift worth $8.
  • 6 of the coupons are for a free gift worth $12.
  • 4 of the coupons are for a free gift worth $40.

Based upon the financial gain or loss over the long run, should you play the game?

  • Yes, I expect to come out ahead in money.
  • No, I expect to come out behind in money.
  • It doesn’t matter. I expect to break even.


The next four questions refer to the following: Recently, a nurse commented that when a patient calls the medical advice line claiming to have the flu , the chance that he/she truly has the flu (and not just a nasty cold) is only about 4%. Of the next 25 patients calling in claiming to have the flu , we are interested in how many actually have the flu .

Define the Random Variable and list its possible values.

X size 12{X} {} = the number of patients calling in claiming to have the flu , who actually have the flu . X size 12{X} {} = 0, 1, 2, ...25

State the distribution of X size 12{X} {} .

B ( 25 , 0 . 04 ) size 12{B \( "25",0 "." "04" \) } {}

Find the probability that at least 4 of the 25 patients actually have the flu .


On average, for every 25 patients calling in, how many do you expect to have the flu ?


The next two questions refer to the following: Different types of writing can sometimes be distinguished by the number of letters in the words used. A student interested in this fact wants to study the number of letters of words used by Tom Clancy in his novels. She opens a Clancy novel at random and records the number of letters of the first 250 words on the page.

What kind of data was collected?

  • qualitative
  • quantitative - continuous
  • quantitative – discrete


What is the population under study?

All words used by Tom Clancy in his novels

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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.
what is the actual application of fullerenes nowadays?
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Source:  OpenStax, Elementary statistics. OpenStax CNX. Dec 30, 2013 Download for free at http://cnx.org/content/col10966/1.4
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