Question

Use the data in Bank Dataset to answer this question.

- Construct a 95% confidence interval for the mean increase in deposits. Note that the population standard deviation σ is not known in this case. Instead the sample standard deviation s should be calculated from the sample and the t distribution should be used.

2. What is the margin of error at the 95% confidence level?

Bank Dataset of Increase in deposits. Mean is 4. Sample size is 152 customers.

4.3

-6.3

1.9

7.7

4.4

5.7

-0.2

-1.6

-1.4

4.6

15.5

-5.5

3.4

0.1

-4.1

1.3

2.7

11.1

4.8

-3.3

0.1

5.3

-1.4

4.1

-1.0

7.6

5.8

2.9

6.7

-1.6

5.6

3.9

2.5

12.5

9.7

9.5

3.8

0.1

0.0

-2.7

2.8

5.0

1.3

15.7

-3.7

5.8

13.4

2.3

1.6

-6.0

7.6

11.0

8.1

6.0

-1.8

-7.4

-4.7

7.0

-7.9

-0.1

15.4

5.6

4.7

7.2

-2.4

-4.4

12.3

11.5

8.1

6.6

6.4

3.6

9.6

-4.1

-2.5

4.8

-4.0

11.8

6.5

2.8

13.8

8.2

3.2

7.6

6.4

4.6

-0.5

4.9

2.0

-6.5

8.7

-2.9

-3.0

5.3

8.5

-2.7

-3.0

-4.5

1.8

12.5

16.6

6.0

9.5

6.2

3.5

-0.7

11.4

4.9

13.1

0.7

5.7

2.8

-7.7

0.2

4.5

14.9

2.7

-2.8

11.0

1.1

8.1

2.4

0.4

1.0

11.3

10.3

0.7

15.6

9.1

10.8

5.6

10.2

10.2

3.3

-2.3

5.1

8.6

7.1

3.5

0.3

-4.6

11.5

4.5

12.1

9.8

5.9

14.9

-7.2

-5.0

-2.2

-2.5

-4.3

9.5

3.8

0.1

0.0

-2.7

2.8

5.0

1.3

15.7

-3.7

5.8

13.4

2.3

1.6

-6.0

7.6

11.0

8.1

6.0

-1.8

-7.4

-4.7

7.0

-7.9

-0.1

15.4

5.6

4.7

7.2

-2.4

-4.4

12.3

11.5

8.1

6.6

6.4

3.6

9.6

-4.1

-2.5

4.8

-4.0

11.8

6.5

2.8

13.8

8.2

3.2

7.6

6.4

4.6

-0.5

4.9

2.0

-6.5

8.7

-2.9

-3.0

5.3

8.5

-2.7

-3.0

-4.5

1.8

12.5

16.6

6.0

9.5

6.2

3.5

-0.7

11.4

4.9

13.1

0.7

5.7

2.8

-7.7

0.2

4.5

14.9

2.7

-2.8

11.0

1.1

8.1

2.4

0.4

1.0

11.3

10.3

0.7

15.6

9.1

10.8

5.6

10.2

10.2

3.3

-2.3

5.1

8.6

7.1

3.5

0.3

-4.6

11.5

4.5

12.1

9.8

5.9

14.9

-7.2

-5.0

-2.2

-2.5

-4.3

Answer #1

Here, n = 152

mean = 4

The sample standard deviation, as calculated with the help of Minitab software, is = 5.948

Now, degrees of freedom = (152 - 1) = 151.

At alpha = 0.05 and df = 151, the critical t value is 1.655

Therefore, 95% confidence interval = t*/n

= 4 1.655 * (5.948/21.236)

=( 4 - 0.801 , 4 + 0.801)

=( 3.199 , 4.801)

margin of error = t*/n

= 1.655 * (5.948/21.236)

= 0.801

We wish to determine the impact of Specification Buying, X11, on
Satisfaction Level, X10. To do so we will split the Hatco data file
into two separate data sets based on the Specification Buying, X11.
This variable has two categories:
1=employs total value analysis approach, evaluating each
purchase separately;
0 = use of specification buying.
Sort the entire Hatco data set based on Specification Buying.
This will create two separate groups of records. Those records with
X11 = 0 and...

7. Using Excel, find the mean and the standard deviation of the
AT&T speeds from the data set #32 Airport Data Speeds. Round
your answers to 3 decimal places. (Show your work!)
mean, x :
standard deviation:
AIRPORT
CODE
VERIZON
SPRINT
AT&T
T-MOBILE
ATL
77.8
0.4
33.9
27.3
AUS
28.5
0.5
29.0
5.1
BNA
1.9
2.3
4.6
9.5
BOS
6.2
1.0
11.7
9.6
BWI
43.0
3.4
12.7
3.2
CLE
15.1
0.5
7.6
24.7
CLT
7.9
1.1
9.1
4.4
CMH
25.7...

An important statistical measurement in service facilities (such
as restaurants and banks) is the variability in service times. As
an experiment, two bank tellers were observed, and the service
times for each of 100 customers were recorded. Do these data allow
us to infer at the 5% significance level that the variance in
service times differs between the two tellers? Estimate with 95%
confidence the ratio of variances of the two bank tellers. Teller 1
Teller 2 7.2 10.9 5.4...

Build a stem-and-leaf plot for these measurements
3.1
4.9
2.8
3.6
2.5
4.5
3.5
3.7
4.1
4.9
2.9
2.1
3.5
4.0
3.7
2.7
4.0
4.4
3.7
4.2
3.8
6.2
2.5
2.9
2.8
5.1
1.8
5.6
2.2
3.4
2.5
3.6
5.1
4.8
1.6
3.6
6.1
4.7
3.9
3.9
4.3
5.7
3.7
4.6
4.0
5.6
4.9
4.2
3.1
3.9
A. Describe the form of data distribution. Do you notice any
unusual results?
B. Use the stem-and-leaf plot to find the minimum
observation....

Year
Unemployment rate
gdp growth
cpi
inflation rate
1980
7.2
-0.2
87
1981
7.6
2.6
94
8.05
1982
9.7
-1.9
97.6
3.83
1983
9.6
4.6
101.3
3.79
1984
7.5
7.3
105.3
3.95
1985
7.2
4.2
109.3
3.80
1986
7.0
3.5
110.5
1.10
1987
6.2
3.5
115.4
4.43
1988
5.5
4.2
120.5
4.42
1989
5.3
3.7
126.1
4.65
1990
5.6
1.9
133.8
6.11
1991
6.9
-0.1
137.9
3.06
1992
7.5
3.6
141.9
2.90
1993
6.9
2.7
145.8
2.75
1994
6.1
4.0...

use the following cell phone airport data speeds:
0.2, 0.2, 0.3, 0.3, 0.4, 0.4, 0.6, 0.7, 0.7, 0.8, 0.8, 0.8,
0.8, 0.9, 0.9, 0.9, 1.3, 1.6, 1.8, 1.8, 1.8, 2.3, 2.5, 2.6, 2.9,
2.9, 3.2, 3.6, 3.8, 4.3, 4.6, 5.6, 5.8, 6.4, 6.5, 6.8, 7.4, 7.5,
7.6, 9.8, 9.9, 10.9, 11.4, 12.3, 12.9, 13.5, 13.7, 14.2, 15.5,
25.2
Q1= ____Mbps

Use the following cell phone airport data speeds (Mbps) from a
particular network. Find the percentile corresponding to the data
speed 6.5 Mbps. 0.1 0.2 0.2 0.2 0.2 0.4 0.5 0.5 0.6 0.6 0.6 0.7 0.7
0.8 0.9 1.2 1.3 1.5 1.6 1.8 1.8 2.3 2.4 2.8 2.8 2.9 2.9 3.3 3.8 4.4
4.6 5.9 6.5 6.8 7.2 7.3 7.8 8.8 9.3 9.6 11.1 11.4 11.4 12.9 13.1
13.3 13.6 13.8 13.9 28.7 Percentile of 6.5equals

Use the following cell phone airport data speeds? (Mbps) from a
particular network. Find Upper P 60.
0.1
0.2
0.2
0.4
0.4
0.5
0.5
0.6
0.6
0.7
0.7
0.7
0.8
0.8
0.8
0.9
1.1
1.6
1.7
1.8
1.8
2.1
2.4
2.5
2.7
2.9
3.4
3.5
3.5
3.9
4.6
4.6
5.7
6.5
7.2
7.5
8.9
10.3
10.5
10.8
11.3
11.4
12.3
12.3
12.9
13.3
14.2
14.8
15.9
28.6

SHOW ALL WORK. DO NOT USE SOFTWARE TO GENERATE ANSWERS.
Calculate the R-chart and X-bar chart limits for the data given
below.
Day
A
B
C
D
1
7.2
8.4
7.9
4.9
2
5.6
8.7
3.3
4.2
3
5.5
7.3
3.2
6.0
4
4.4
8.0
5.4
7.4
5
9.7
4.6
4.8
5.8
6
8.3
8.9
9.1
6.2
7
4.7
6.6
5.3
5.8
8
8.8
5.5
8.4
6.9
9
5.7
4.7
4.1
4.6
10
3.7
4.0
3.0
5.2
11
2.6
3.9...

Use the standard normal distribution or the t-distribution to
construct a 95% confidence interval for the population. In a
recent season, the population standard deviation of the yards per
carry for all running backs was 1.27. The yards per carry of 25
randomly selected running backs are shown below. Assume the yards
per carry are normally distributed. 1.9 2.7 5.8 4.9 7.4 6.6 6.1 3.4
3.8 1.3 1.6 4.9 2.8 6.8 5.1 6.1 3.1 6.8 4.9 6.6 4.3 7.3 5.6...

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