Fuming because you are stuck in traffic? Roadway congestion is a costly item, both in time wasted and fuel wasted. Let x represent the average annual hours per person spent in traffic delays and let y represent the average annual gallons of fuel wasted per person in traffic delays. A random sample of eight cities showed the following data. x (hr) 26 5 21 36 18 22 16 5 y (gal) 47 3 34 56 32 36 26 9 (a) Draw a scatter diagram for the data.  Flash Player version 10 or higher is required for this question. You can get Flash Player free from Adobe's website.   Verify that Σx = 149, Σx2 = 3527, Σy = 243, Σy2 = 9587, and Σxy = 5796.Compute r. The data in part (a) represent average annual hours lost per person and average annual gallons of fuel wasted per person in traffic delays. Suppose that instead of using average data for different cities, you selected one person at random from each city and measured the annual number of hours lost x for that person and the annual gallons of fuel wasted y for the same person. x (hr) 21 4 19 43 19 27 2 38 y (gal) 63 8 14 50 24 34 4 71 (b) Compute x and y for both sets of data pairs and compare the averages.   x y Data 1     Data 2     Compute the sample standard deviations sx and sy for both sets of data pairs and compare the standard deviations.   sx sy Data 1     Data 2     In which set are the standard deviations for x and y larger? The standard deviations for x and y are larger for the first set of data. The standard deviations for x and y are larger for the second set of data.  The standard deviations for x and y are the same for both sets of data. Look at the defining formula for r. Why do smaller standard deviations sx and sy tend to increase the value of r? Dividing by smaller numbers results in a smaller value. Multiplying by smaller numbers results in a larger value. Multiplying by smaller numbers results in a smaller value. Dividing by smaller numbers results in a larger value. (c) Make a scatter diagram for the second set of data pairs.  Flash Player version 10 or higher is required for this question. You can get Flash Player free from Adobe's website.   Verify that Σx = 173, Σx2 = 5205, Σy = 268, Σy2 = 13,518, and Σxy = 7851.Compute r. (d) Compare r from part (a) with r from part (b). Do the data for averages have a higher correlation coefficient than the data for individual measurements? No, the data for averages do not have a higher correlation coefficient than the data for individual measurements. Yes, the data for averages have a higher correlation coefficient than the data for individual measurements.     List some reasons why you think hours lost per individual and fuel wasted per individual might vary more than the same quantities averaged over all the people in a city.

MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
icon
Related questions
icon
Concept explainers
Topic Video
Question

Fuming because you are stuck in traffic? Roadway congestion is a costly item, both in time wasted and fuel wasted. Let x represent the average annual hours per person spent in traffic delays and let y represent the average annual gallons of fuel wasted per person in traffic delays. A random sample of eight cities showed the following data.

x (hr) 26 5 21 36 18 22 16 5
y (gal) 47 3 34 56 32 36 26 9
(a) Draw a scatter diagram for the data.

 
Flash Player version 10 or higher is required for this question. 
You can get Flash Player free from Adobe's website.

 

Verify that Σx = 149, Σx2 = 3527, Σy = 243, Σy2 = 9587, and Σxy = 5796.

Compute r.

The data in part (a) represent average annual hours lost per person and average annual gallons of fuel wasted per person in traffic delays. Suppose that instead of using average data for different cities, you selected one person at random from each city and measured the annual number of hours lost x for that person and the annual gallons of fuel wasted y for the same person.

x (hr) 21 4 19 43 19 27 2 38
y (gal) 63 8 14 50 24 34 4 71
(b) Compute x and y for both sets of data pairs and compare the averages.
  x y
Data 1    
Data 2    

Compute the sample standard deviations sx and sy for both sets of data pairs and compare the standard deviations.
  sx sy
Data 1    
Data 2    
In which set are the standard deviations for x and y larger?
The standard deviations for x and y are larger for the first set of data.
The standard deviations for x and y are larger for the second set of data.  The standard deviations for x and y are the same for both sets of data.

Look at the defining formula for r. Why do smaller standard deviations sx and sy tend to increase the value of r?
Dividing by smaller numbers results in a smaller value.
Multiplying by smaller numbers results in a larger value.
Multiplying by smaller numbers results in a smaller value.
Dividing by smaller numbers results in a larger value.

(c) Make a scatter diagram for the second set of data pairs.

 
Flash Player version 10 or higher is required for this question. 
You can get Flash Player free from Adobe's website.

 

Verify that Σx = 173, Σx2 = 5205, Σy = 268, Σy2 = 13,518, and Σxy = 7851.

Compute r.
 

(d) Compare r from part (a) with r from part (b). Do the data for averages have a higher correlation coefficient than the data for individual measurements?
No, the data for averages do not have a higher correlation coefficient than the data for individual measurements.
Yes, the data for averages have a higher correlation coefficient than the data for individual measurements.    

List some reasons why you think hours lost per individual and fuel wasted per individual might vary more than the same quantities averaged over all the people in a city. 
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 9 steps with 7 images

Blurred answer
Knowledge Booster
Centre, Spread, and Shape of a Distribution
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, statistics and related others by exploring similar questions and additional content below.
Similar questions
Recommended textbooks for you
MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
Statistics
ISBN:
9781119256830
Author:
Amos Gilat
Publisher:
John Wiley & Sons Inc
Probability and Statistics for Engineering and th…
Probability and Statistics for Engineering and th…
Statistics
ISBN:
9781305251809
Author:
Jay L. Devore
Publisher:
Cengage Learning
Statistics for The Behavioral Sciences (MindTap C…
Statistics for The Behavioral Sciences (MindTap C…
Statistics
ISBN:
9781305504912
Author:
Frederick J Gravetter, Larry B. Wallnau
Publisher:
Cengage Learning
Elementary Statistics: Picturing the World (7th E…
Elementary Statistics: Picturing the World (7th E…
Statistics
ISBN:
9780134683416
Author:
Ron Larson, Betsy Farber
Publisher:
PEARSON
The Basic Practice of Statistics
The Basic Practice of Statistics
Statistics
ISBN:
9781319042578
Author:
David S. Moore, William I. Notz, Michael A. Fligner
Publisher:
W. H. Freeman
Introduction to the Practice of Statistics
Introduction to the Practice of Statistics
Statistics
ISBN:
9781319013387
Author:
David S. Moore, George P. McCabe, Bruce A. Craig
Publisher:
W. H. Freeman