Question

In a test of braking performance, a tire manufacturer measured the stopping distance for one of its tire models. On a test track, a car made repeated stops from 60 miles per hour. The test was run on both dry and wet pavement, with results as shown below. Stopping Distance (ft) Wet 213 192 210 201 198 203 204 177 187 218 Dry 154 148 137 144 131 151 133 136 139 128 a) Construct a 95% confidence interval for the mean dry pavement stopping distance.

The confidence interval is

Answer #1

Sol:

For the given dry pavement sample

Dry 154 148 137 144 131 151 133 136 139 128

sample mean=xbar=1401/10=140.1

sample standard deviation=s=8.799621

sample size=n=10

alpha=1-0.95=0.05

alpha/2=0.05/2=0.025

df=n-1=10-1=9

t critical value in excel

==T.INV(0.025,9)

=2.262157163

95% confidence interval for mean is

xbar-t*s/sqrt(n),xbar+t*s/sqrt(n)

140.1-2.262157163*8.799621/sqrt(10),140.1+2.262157163*8.799621/sqrt(10)

133.8051, 146.3949

95% lower limit mean dry pavement stopping distance=133.8051

95% upper limit mean dry pavement stopping distance.=146.3949

An engineer wishes to determine if the stopping distance for
midsize automobiles is different from that of compact automobiles
at 75 mph. The data is shown below.
Automobile
Midsize
Compact
1
188
200
2
190
211
3
195
206
4
192
297
5
186
198
6
194
204
7
188
218
8
187
212
9
214
196
10
203
193
a) State the null and alternate hypotheses.
b) Use a Wilcoxon rank sum test to determine if there is a...

Refer to the accompanying data set of mean drive-through
service times at dinner in seconds at two fast-food restaurants.
Construct a
95% confidence interval estimate of the mean drive-through
service time for Restaurant X at dinner; then do the same for
Restaurant Y. Compare the results.
Restaurant X
Restaurant Y
85
85
116
116
118
118
146
146
270
270
100
100
124
124
156
156
118
118
176
176
184
184
125
125
154
154
166
166
211
211...

Refer to the accompanying data set of mean drive-through
service times at dinner in seconds at two fast-food restaurants.
Construct a
99% confidence interval estimate of the mean drive-through
service time for Restaurant X at dinner; then do the same for
Restaurant Y. Compare the results.
Service Times (seconds)
Restaurant X
Restaurant Y
80
80
124
124
118
118
147
147
264
264
102
102
127
127
155
155
112
112
174
174
183
183
119
119
149
149
164...

Refer to the accompanying data set of mean drive-through
service times at dinner in seconds at two fast food restaurants.
Construct a 95% confidence interval estimate of the mean
drive-through service time for Restaurant X at dinner; then do the
same for Restaurant Y. Compare the results.
Restaurant X
Restaurant Y
85
102
125
130
115
149
141
111
265
174
185
138
126
113
151
123
165
131
212
127
337
137
311
139
176
226
117
218
161...

Pat.#
Before
After
1
195
125
To the left is 2 datasets measured for
a sample of 107 patients with the high cholesterol level before and
after taking medication. Obtain the following for both sets:
2
208
164
3
254
152
1- the mean, mode and median
4
226
144
5
290
212
2- the variance and standard
deviation
6
239
171
7
216
164
3- First, second and third
quartiles
8
286
200
9
243
190
10
217
130...

Open Three Hospitals data. SETUP: It is
believed that the number of injuries recorded in hospital 1 is
different from the number of injuries recorded in hospital 2. Given
the data your job is to confirm or disprove this assertion.
10. What test/procedure did you perform? (4
points)
a. Regression
b. Two sided t-test
c. One sided t-test
d. Confidence Interval
11. What is the statistical interpretation? (4
points)
a. Average of data is inconsistent with the claim
b. P-value...

A loan made on March 14 is due September 13 of the following
year. Find the exact time for the loan in a non-leap year and a
leap year.
days.
The exact time in a non-leap year is ? days
The exact time in a leap year is ? days.
Data Table
Sequential Numbers for Dates of the Year
Day of Month
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
1
1
32
60
91
121...

The Red Lobster Restaurant chain conducts regular surveys of its
customers to monitor the performance of individual restaurants. One
of the questions asks customers to rate the overall quality of
their last visit. the listed responses are Poor 1, Fair 2, Good 3,
Very Good 4, and Excellent 5. The survey also asks respondents
whether their children accompanied them (1=yes) and (2=no).
Graphically depict these data and describe your findings.
Customer
Rate
Children
1
4
1
2
3
2
3...

Part C: Regression and Correlation Analysis
Use the dependent variable (labeled Y) and the independent
variables (labeled X1, X2, and X3) in the data file. Use Excel to
perform the regression and correlation analysis to answer the
following.
Generate a scatterplot for the specified dependent variable (Y)
and the X1 independent variable, including the graph of the "best
fit" line. Interpret.
Determine the equation of the "best fit" line, which describes
the relationship between the dependent variable and the selected...

Use the dependent variable (labeled Y) and the independent
variables (labeled X1, X2, and X3) in the data file. Use Excel to
perform the regression and correlation analysis to answer the
following.
Generate a scatterplot for the specified dependent variable (Y)
and the X1 independent variable, including the graph of the "best
fit" line. Interpret.
Determine the equation of the "best fit" line, which describes
the relationship between the dependent variable and the selected
independent variable.
Determine the coefficient of...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 52 seconds ago

asked 4 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 3 hours ago