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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 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
  • A box plot with a whisker between 0 and 1, a dotted line at 1, a solid line at 2, and a whisker between 2 and 4.
  • 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 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
  • A box plot with a whisker between 0 and 3, a solid line at 3, a dashed line at 4, a solid line at 5, and a whisker between 5 and 7.
  • 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, μ .
    • the population standard deviation, σ .
    • 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
  • A box plot with a whisker between 174 and 205.5, a solid line at 205.5, a dashed line at 241, a solid line at 272.5, and a whisker between 272.5 and 302.
  • 205.5, 272.5
  • sample
  • population
    • 236.34
    • 37.50
    • 161.34
    • 0.84 std. dev. below the mean
  • Young

Questions & Answers

I'm interested in biological psychology and cognitive psychology
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physiological Psychology
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How can I develope my cognitive domain
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Dakolo Reply
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
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Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
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Wekolamo
because it helps many people around the world to understand how to interact with other people and understand them well, for example at work (job).
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ARC
A child is a member of community not society elucidate ?
JESSY Reply
Isn't practices worldwide, be it psychology, be it science. isn't much just a false belief of control over something the mind cannot truly comprehend?
Simon Reply
compare and contrast skinner's perspective on personality development on freud
namakula Reply
Skinner skipped the whole unconscious phenomenon and rather emphasized on classical conditioning
war
explain how nature and nurture affect the development and later the productivity of an individual.
Amesalu Reply
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills
Zyryn Reply
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Jonathan
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Jonathan
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interpersonal relationships
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Source:  OpenStax, Collaborative statistics (with edits: teegarden). OpenStax CNX. Jul 20, 2009 Download for free at http://legacy.cnx.org/content/col10561/1.3
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