1. To compare commuting times in various locations, independent random samples were obtained from the six cities presented in the “Longest Commute to Work” graphic on page 255 in your textbook. The samples were from workers who commute to work during the 8:00 a.m. rush hour. Oneway Travel to Work in Minutes
Atlanta 
Boston 
Dallas 
Philadelphia 
Seattle 
St. Louis 
29 
18 
42 
29 
30 
15 
21 
37 
25 
20 
23 
24 
20 
27 
26 
33 
31 
42 
15 
25 
32 
37 
39 
23 
37 
32 
20 
42 
14 
33 
26 
34 
26 


18 

48 
35 



a. Construct a graphic representation of the data using six sidbyside dotplots.
b. Visually estimate the mean commute time for each city and locate it with an X.
c. Does it appear that different citites have different effects on the average amount of time spent by workers who commute to work during the 8:00 a.m. rush hour? Explain.
d. Does it visually appear that different cities have different effects on the variation in the amount of time spent by workers wo commute to work during the 8:00 a.m. rush hour? Explain.
Part 2
a. Calculate the mean commute time for each city depicted.
b. Does there seem to be a difference among the mean oneway commute times for these six cities?
c. Calculate the standard deviation for each city’s commute time.
d. Does there seem to be a difference among the standard deviations between the oneway commute times for these six cities?
Part 3
a. Construct the 95% confidence interval for the mean commute time for Atlanta and Boston.
b. Based on the confidence intervals found does it appear that the mean commute time is the same or different for these two cities (Atlanta and Boston). Explain
c. Construct the 95% confidence interval for the mean commute time for Dallas.
d. Based on the confidence intervals found in (Atlanta and Boston) and Dallas does it appear that the mean commute time is the same or different for Boston and dalls? Explain.
e. Based on the confidence levels found in (Atlanta and Boston) and (Dallas) does it appear that the mean commute time is the same or different for the set of three cities, Atlanta, Boston, and Dallas? Explain
f. How doe your confidence intervals compare to the intervals given for Atlant, Boston, and Dallas in “Longest Commute to Work” on page 255?
Question 4.1
2. Interstate 90 is the longest of the eastwest U.S. interstate highways with its 3,112 miles stretching from Boston, MA at I93 on the eastern end to Seattle WA at the Kingdome on the western end. It travels across 13 northern states; the number of miles and number of intersections in each of those states is listed below.
State 
No. of Inter 
Miles 
WA 
57 
298 
ID 
15 
73 
MT 
83 
558 
WY 
23 
207 
SD 
61 
412 
MN 
52 
275 
WI 
40 
188 
IL 
19 
103 
IN 
21 
157 
OH 
40 
244 
PA 
14 
47 
NY 
48 
391 
MA 
18 
159 
a. Construct a scatter diagram of the data.
b. Find the equation for the line of best fit using x= miles and y=intersections.
c. Using the equation found in part (b), estimate the average number of intersections per mile along I90.
d. Find a 95% confidence interval for β_{1}.
e. Explain the meaning of the interval found in part d.
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