# 2.14 Univariate descriptive statistics: homework

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Descriptive Statistics: Homework is part of the collection col10555 written by Barbara Illowsky and Susan Dean and provides homework questions related to lessons about descriptive statistics.

Twenty-five randomly selected students were asked the number of movies they watched the previous week. The results are as follows:

# of movies Frequency Relative Frequency Cumulative Relative Frequency
0 5
1 9
2 6
3 4
4 1

• Find the sample mean $\overline{x}$
• Find the sample standard deviation, $s$
• Construct a histogram of the data.
• Complete the columns of the chart.
• Find the first quartile.
• Find the median.
• Find the third quartile.
• Construct a box plot of the data.
• What percent of the students saw fewer than three movies?
• Find the 40th percentile.
• Find the 90th percentile.
• Construct a line graph of the data.
• Construct a stem plot of the data.
• 1.48
• 1.12
• 1
• 1
• 2
• 80%
• 1
• 3

The median age for U.S. blacks currently is 30.9 years; for U.S. whites it is 42.3 years. (( Source: http://www.usatoday.com/news/nation/story/2012-05-17/minority-births-census/55029100/1) )

• Based upon this information, give two reasons why the black median age could be lower than the white median age.
• Does the lower median age for blacks necessarily mean that blacks die younger than whites? Why or why not?
• How might it be possible for blacks and whites to die at approximately the same age, but for the median age for whites to be higher?

Forty randomly selected students were asked the number of pairs of sneakers they owned. Let X = the number of pairs of sneakers owned. The results are as follows:

X Frequency Relative Frequency Cumulative Relative Frequency
1 2
2 5
3 8
4 12
5 12
7 1
• Find the sample mean $\overline{x}$
• Find the sample standard deviation, $s$
• Construct a histogram of the data.
• Complete the columns of the chart.
• Find the first quartile.
• Find the median.
• Find the third quartile.
• Construct a box plot of the data.
• What percent of the students owned at least five pairs?
• Find the 40th percentile.
• Find the 90th percentile.
• Construct a line graph of the data
• Construct a stem plot of the data
• 3.78
• 1.29
• 3
• 4
• 5
• 32.5%
• 4
• 5

600 adult Americans were asked by telephone poll, What do you think constitutes a middle-class income?The results are below. Also, include left endpoint, but not the right endpoint. ( Source: Time magazine; survey by Yankelovich Partners, Inc. )

"Not sure" answers were omitted from the results.
Salary ($) Relative Frequency <20,000 0.02 20,000 - 25,000 0.09 25,000 - 30,000 0.19 30,000 - 40,000 0.26 40,000 - 50,000 0.18 50,000 - 75,000 0.17 75,000 - 99,999 0.02 100,000+ 0.01 • What percent of the survey answered "not sure"? • What percent think that middle-class is from$25,000 - \$50,000 ?
• Construct a histogram of the data
1. Should all bars have the same width, based on the data? Why or why not?
2. How should the<20,000 and the100,000+ intervals be handled? Why?
• Find the 40th and 80th percentiles
• Construct a bar graph of the data

Following are the published weights (in pounds) of all of the team members of the San Francisco 49ers from a previous year ( Source: San Jose Mercury News )

• 177
• 205
• 210
• 210
• 232
• 205
• 185
• 185
• 178
• 210
• 206
• 212
• 184
• 174
• 185
• 242
• 188
• 212
• 215
• 247
• 241
• 223
• 220
• 260
• 245
• 259
• 278
• 270
• 280
• 295
• 275
• 285
• 290
• 272
• 273
• 280
• 285
• 286
• 200
• 215
• 185
• 230
• 250
• 241
• 190
• 260
• 250
• 302
• 265
• 290
• 276
• 228
• 265

• Organize the data from smallest to largest value.
• Find the median.
• Find the first quartile.
• Find the third quartile.
• Construct a box plot of the data.
• The middle 50% of the weights are from _______ to _______.
• If our population were all professional football players, would the above data be a sample of weights or the population of weights? Why?
• If our population were the San Francisco 49ers, would the above data be a sample of weights or the population of weights? Why?
• Assume the population was the San Francisco 49ers. Find:
• the population mean, $\mu$ .
• the population standard deviation, $\sigma$ .
• the weight that is 2 standard deviations below the mean.
• When Steve Young, quarterback, played football, he weighed 205 pounds. How many standard deviations above or below the mean was he?
• That same year, the mean weight for the Dallas Cowboys was 240.08 pounds with a standard deviation of 44.38 pounds. Emmit Smith weighed in at 209 pounds. With respect to his team, who was lighter, Smith or Young? How did you determine your answer?
• 241
• 205.5
• 272.5
• 205.5, 272.5
• sample
• population
• 236.34
• 37.50
• 161.34
• 0.84 std. dev. below the mean
• Young

are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
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
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
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
how did you get the value of 2000N.What calculations are needed to arrive at it
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