This module provides homework questions related to lessons on descriptive statistics. The original module by Dr. Barbara Illowsky and Susan Dean has been modified by Roberta Bloom. Some homework questions have been changed and/or added.
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
Find the sample standard deviation,
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.
1.48
1.12
1
1
2
80%
1
3
The median age for U.S. blacks currently is 30.1 years; for U.S. whites it is 36.6 years. (Source: U.S. Census)
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
Find the sample standard deviation,
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.
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
Should all bars have the same width, based on the data? Why or why not?
How should the<20,000
and the100,000+
intervals be handled? Why?
Find the 40th and 80th percentiles
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,
.
the population standard deviation,
.
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 average 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?
Based on the shape of the data, what is the most appropriate measure of center for this data: mean, median, or mode? Explain.
Are there any outliers in the data? Use an appropriate numerical test involving the
IQR to identify outliers, if any, and clearly state your conclusion.
Are any data values further away than 2 standard deviations from the mean? Clearly state your conclusion and show numerical work to justify 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
The mean is most appropriate. From the boxplot the data appear to be relatively symmetric. When the data are symmetric, it is appropriate to use the mean because it incorporates more information from the data. (If the data were skewed, then it would be more appropriate to use the median; but these data are not skewed.)
IQR = 272.5 – 202.5 = 67; Q1 – 1.5*IQR = 205.5 – 1.5(67) = 105; Q3 + 1.5*IQR = 272.5 + 1.5(67) = 373.
All weights are between 105 and 373. There are no outliers.
Mean – 2(standard deviation) = 240.08 – 2(44.38) = 151.32 ;
Mean + 2(standard deviation) = 240.08 + 2(44.38) = 328.84 ;All players' weights are between 2 standard deviations above and below the mean.
Questions & Answers
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
Receive real-time job alerts and never miss the right job again
Source:
OpenStax, Collaborative statistics homework book: custom version modified by r. bloom. OpenStax CNX. Dec 23, 2009 Download for free at http://legacy.cnx.org/content/col10619/1.2
Google Play and the Google Play logo are trademarks of Google Inc.
Notification Switch
Would you like to follow the 'Collaborative statistics homework book: custom version modified by r. bloom' conversation and receive update notifications?
