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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

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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?
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
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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