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. One-way Travel to Work in Minutes
|
Atlanta |
Boston |
Dallas |
Philadelphia |
Seattle |
St. |
|
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 side-by-side dotplots.
b. Visually estimate the mean commute
time for each city and locate it with an X.
c. Does it appear that different cities
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 who 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 one-way 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 one-way 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 Dallas? 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
Question
2
2.Interstate 90 is the longest of the
east-west U.S. interstate highways with its 3,112 miles stretching from Boston,
MA at I-93 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 I-90.
d. Find a 95% confidence interval for
?1.
