Homework 6 Attempt 3
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School
American Military University *
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Course
302
Subject
Statistics
Date
Jan 9, 2024
Type
docx
Pages
19
Uploaded by DeanHippopotamus5891
Question 1
1 / 1 point
A researcher is testing reaction times between the dominant and non-dominant hand. They randomly start with each hand for 20
subjects and their reaction times in milliseconds are recorded. Test to see if the reaction time is faster for the dominant hand using
a 5% level of significance. The hypotheses are:
H
0
: μ
D
= 0
H
1
: μ
D
> 0
t-Test: Paired Two Sample for Means
Non-
Dominant Dominant
Mean
63.33
56.28
Variance
218.96431
58
128.75221
05
Observations
20
20
Pearson Correlation
0.9067
Hypothesized Mean
Difference
0
df
19
t Stat
4.7951
P(T<=t) one-tail
0.0001
t Critical one-tail
1.7291
P(T<=t) two-tail
0.0001
t Critical two-tail
2.0930
What is the correct decision?
Reject H
0
Accept H
0
Reject H
1
Accept H
1
Do not reject H
0
Hide question 1 feedback
The p-value for a one tailed test is 0.0001. This is given to you in the output. No calculations are needed. 0.0001 < .05, Reject Ho, this
is significant.
Question 2
1 / 1 point
A manager wants to see if it is worth going back for an MBA degree. They randomly sample 18 managers' salaries before and after
undertaking a MBA degree and record their salaries in thousands of dollars. Assume Salaries are normally distributed. Test the claim
that the MBA degree, on average, increases a manager's salary. Use a 10% level of significance.
t-Test: Paired Two Sample for Means
New
Salary
Old
Salary
Mean
59.82778
52.66667
Variance
175.5551 112.7012
Observations
18
18
Pearson Correlation
0.7464
Hypothesized Mean Difference
0
df
17
t Stat
3.4340
P(T<=t) one-tail
0.0016
t Critical one-tail
1.3334
P(T<=t) two-tail
0.0033
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t Critical two-tail
1.7396
The hypotheses for this problem are:
H
0
: μ
D
= 0
H
1
: μ
D
> 0
What is the correct p-value?
0.0033
0.0016
-1.3334
-3.4340
0.7464
Hide question 2 feedback
No calculations are needed. The answer is given to you in the output.
P(T<=t) one-tail 0.0016
Question 3
1 / 1 point
A math teacher tells her students that eating a healthy breakfast on a test day will help their brain function and perform well on
their test. During finals week, she randomly samples 45 students and asks them at the door what they ate for breakfast. She
categorizes 25 students into Group 1 as those who ate a healthy breakfast that morning and 20 students into Group 2 as those who
did not. After grading the final, she finds that 48% of the students in Group 1 earned an 80% or higher on the test, and 40% of the
students in Group 2 earned an 80% or higher. Can it be concluded that eating a healthy breakfast improves test scores? Use a 0.05
level of significance.
Hypotheses:
H
0
:
p
1
=
p
2
H
1
:
p
1
>
p
2
In this scenario, what is the p-value? (Round to 4 decimal places)
p-value =
___
0.2958
___
Hide question 3 feedback
z =.48−.40.4444
∗
.5556
∗
(1/25+1/20)
z = 0.536656
Use NORM.S.DIST(0.536656,TRUE) to find the for the lower tailed test.
0.704247, then 1 - 0.704247, this is the p-value you want to use for an upper tailed test.
Question 4
1 / 1 point
The manager at a sports radio station will be covering several football games over the weekend. She knows that most of her
listeners are at least 22 years old and wants to know what age group she should gear her advertisements to for the games. She
takes a random sample of 45 listeners from age 22-39 and 55 listeners who are 40 and older and asks them if they are likely to
tune in to football games. The "yes" responses are recorded below.
Age 22-39 (Group 1)
Age 40+ (Group 2)
Responded "Yes" to Football
32
44
Sample Size n
45
55
At the 0.05 level of significance, we are attempting to investigate if there is a significant difference in the proportion of listeners
based on age.
Enter the
P
-Value - round to 4 decimal places.
p-value =
___
0.3005
___
Hide question 4 feedback
This is a two tailed test because you want to find significant difference.
z = .71111−.80.76
∗
.24
∗
(1/45+1/55)
z = -1.03543
Use NORM.S.DIST(-1.03543,TRUE) to find the for the lower tailed test.
This value is smaller of the two, thus you will multiply it by 2 for a two tailed test
0.150233*2, this is the p-value you want to use for the conclusion.
Question 5
1 / 1 point
Two competing toothpaste brands both claim to produce the best toothpaste for whitening. A dentist randomly samples 48 patients
that use Brand A (Group 1) and finds 30 of them are satisfied with the whitening results of the toothpaste. She then randomly
samples 45 patients that use Brand B (Group 2) and finds 33 of them are satisfied with the whitening results of the toothpaste.
Construct a 99% confidence interval for the difference in proportions and use it to decide if there is a significant difference in the
satisfaction level of patients.
Enter the confidence interval - round to 3 decimal places.
___
-0.356
___
(50 %)
<
p
1
-
p
2
<
___
0.139
___
(
50 %)
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Hide question 5 feedback
Z-Critical Value =NORM.S.INV(.995) = 2.575
LL = (.625-.7333) - 2.575*.625
∗
.37548+.7333
∗
.266745
UL = (.625-.7333) + 2.575*.625
∗
.37548+.7333
∗
.266745
Question 6
1 / 1 point
Match the Symbol with the correct phrase.
__
1
__
Reduced
__
4
__
More than
__
2
__
At most
__
3
__
At least
__
5
__
Different from
1
.
<
2
.
≤
3
.
≥
4
.
>
5
.
≠
Hide question 6 feedback
Reduced is less than
At most means you can not have any more than that amount. That is the most you are allowed to have.
At least, this is the least amount you can have but you can have more than the least amount.
More than is greater
Different from is not equal
Question 7
1 / 1 point
A null hypothesis can only be rejected at the 5% significance level if and only if:
a 95% confidence interval includes the hypothesized value of the parameter
a 95% confidence interval does not include the hypothesized value of the parameter
the null hypotheses includes sampling error
the null hypothesis is biased
Question
8
1 / 1
point
A lab technician is tested for her consistency by taking multiple measurements of cholesterol levels from
the same blood sample. The target accuracy in the past has been 2.5 or less with a standard deviation
of 1.15. If the lab technician takes 16 measurements and the variance of the measurements in the
sample is 2.2, does this provide enough evidence to reject the claim that the lab technician's accuracy is
within the target accuracy?
State the null and alternative hypotheses.
H
0
: µ ≠ 2.5, H
1
: µ = 2.5
H
0
: µ
≤
2.5, H
1
: µ > 2.5
H
0
:
µ
≥ 2.5, H
1
:
µ
< 2.5
H
0
:µ
<
2.5, H
1
: µ ≠ 2.5
Hide question 8 feedback
The hypothesized value is 2.5 and the keyword is less which makes this a lower tailed test.
Question 9
1 / 1 point
Results from previous studies showed 79% of all high school seniors from a certain city plan to attend
college after graduation. A random sample of 200 high school seniors from this city reveals that 162
plan to attend college. Does this indicate that the percentage has increased from that of previous
studies? Test at the 5% level of significance.
What is the p-value associated with your test of hypothesis?
0.7563
0.6874
0.4874
0.2437
Hide question 9 feedback
Hypothesized value is .79 and this is an upper tailed test because of the keyword increased
z = .81−.79.79
∗
.21200
z = 0.694419
NORM.S.DIST(0.694419,TRUE) = 0.75629. This is the p-value for a lower tailed test. To find the p-value for an upper tailed take 1 -
0.75629. Use this value for the conclusion
Question 10
1 / 1 point
The alternative hypothesis is also known as the:
research hypothesis
null hypothesis
elective hypothesis
optional hypothesis
Question
11
1 / 1
point
A movie theater company wants to see if there is a difference in the average movie ticket sales in San Diego and Portland per
week. They sample 20 sales from San Diego and 20 sales from Portland over a week. Test the claim using a 5% level of
significance. Assume the variances are unequal and that movie sales are normally distributed.
San Diego
Portland
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221
209
221
214
206
223
213
221
226
218
243
214
182
222
229
220
214
223
233
222
231
233
217
219
219
226
234
226
239
219
235
228
211
211
239
216
221
219
234
209
The Hypotheses for this problem are:
H
0
: μ
1
= μ
2
H
1
: μ
1
μ
2
Find the p-value. Round answer to 4 decimal places. Make sure you put the 0 in front of the decimal.
p-value =___
___
Answer:
0.2853
Hide question 11 feedback
Use the Data Analysis Toolpak in Excel.
Data -> Data Analysis -> scroll to where is says t:Test 2 Samples Assuming Unequal Variances -> OK
Variable Input 1: is San Diego
Variable Input 2: is Portland
The Hypothesized Mean Difference is 0 and make sure you click Labels in the first row and click OK. You will get an output and this
is the p-value you are looking for.
P(T<=t) two-tail 0.2853
Question 12
1 / 1 point
A researcher takes sample temperatures in Fahrenheit of 17 days from New York City and 18 days from Phoenix. Test the claim
that the mean temperature in New York City is different from the mean temperature in Phoenix. Use a significance level of
α=0.05. Assume the populations are approximately normally distributed with unequal variances. You obtain the following two
samples of data.
New York
City
Phoenix
99
94.2
95.5
72
93.2
86.8
102
122.1
85.4
114.4
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80
94.7
86.4
89.7
75.4
104.7
79.5
77.6
83.4
106.8
64.3
98.6
65.5
91.5
87.7
82
104
97.7
74.3
64.9
59.5
82
82.8
72
116.2
The Hypotheses for this problem are:
H
0
: μ
1
= μ
2
H
1
: μ
1
μ
2
Find the p-value. Round answer to 4 decimal places. Make sure you put the 0 in front of the decimal.
p-value =___
___
Answer:
0.0705
Hide question 12 feedback
Use the Data Analysis Toolpak in Excel.
Data - > Data Analysis -> scroll to where is says t:Test 2 Samples Assuming Unequal Variances -> OK
Variable Input 1: is New York
Variable Input 2: is Phoenix
The Hypothesized Mean Difference is 0 and make sure you click Labels in the first row and click OK. You will get an output and this
is the p-value you are looking for.
P(T<=t) two-tail 0.0705
Question 13
1 / 1 point
You are testing the claim that the mean GPA of night students is different from the mean GPA of day students. You sample 30
night students, and the sample mean GPA is 2.35 with a standard deviation of 0.46. You sample 25 day students, and the sample
mean GPA is 2.58 with a standard deviation of 0.47. Test the claim using a 5% level of significance. Assume the sample standard
deviations are unequal and that GPAs are normally distributed.
Hypotheses:
H
0
: μ
1
(?)
μ
2
H
1
: μ
1
(?)
μ
2
What are the correct hypotheses for this problem?
H
0
: μ
1
≠ μ
2
; H
1
: μ
1
=
μ
2
H
0
: μ
1
≤ μ
2
; H
1
: μ
1
≥
μ
2
H
0
: μ
1
< μ
2
; H
1
: μ
1
=
μ
2
H
0
: μ
1
= μ
2
; H
1
:μ
1
≠
μ
2
H
0
: μ
1
= μ
2
; H
1
: μ
1
>
μ
2
H
0
: μ
1
≥ μ
2
; H
1
: μ
1
≤
μ
2
Hide question 13 feedback
This is a two tailed test because the keyword is different.
This is a two tailed test because the keyword is different.
Question 14
1 / 1 point
In a two-tailed 2-sample z-test you find a P-Value of 0.0278. At what level of
significance would you choose to reject the null hypothesis? Select all that apply.
0.05
0.08
0.10
0.01
Hide question 14 feedback
If the p-value < alpha, then you Reject the Null and it is significant.
0.0278 < .05, .08 and .10.
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If the p-value < alpha, then you Reject the Null and it is significant.
0.0278 < .05, .08 and .10.
If the p-value < alpha, then you Reject the Null and it is significant.
0.0278 < .05, .08 and .10.
Question 15
1 / 1 point
Which of the following is a requirement that must first be satisfied before running a z-
test for the difference between two means?
The standard deviations for both populations must be known.
The standard deviations should come from each sample.
The samples must be dependent.
The populations must be approximately normal.
Question
16
1 / 1
point
In a random sample of 50 Americans five years ago (Group 1), the average credit card
debt was $5,798. In a random sample of 50 Americans in the present day (Group 2),
the average credit card debt is $6,511. Let the population standard deviation be
$1,154 five years ago, and let the current population standard deviation be $1,645.
Using a 0.01 level of significance, test if there is a difference in credit card debt today
versus five years ago.
What are the correct hypotheses for this problem?
H
0
: μ
1
= μ
2
; H
1
: μ
1
≠
μ
2
H
0
: μ
1
≤ μ
2
; H
1
: μ
1
≥
μ
2
H
0
: μ
1
≠ μ
2
; H
1
: μ
1
=
μ
2
H
0
: μ
1
≥ μ
2
; H
1
: μ
1
≤
μ
2
H
0
: μ
1
= μ
2
; H
1
: μ
1
>
μ
2
H
0
: μ
1
< μ
2
; H
1
: μ
1
=
μ
2
Hide question 16 feedback
This is a two tailed test because of the keyword difference.
Question 17
1 / 1 point
A survey found that the average daily cost to rent a car in Los Angeles is $102.24 and in Las Vegas is $97.35. The data were
collected from two random samples of 40 in each of the two cities and the population standard deviations are $5.98 for Los
Angeles and $4.21 for Las Vegas. At the 0.05 level of significance, construct a confidence interval for the difference in the means
and then decide if there is a significant difference in the rates between the two cities. Let the sample from Los Angeles be Group 1
and the sample from Las Vegas be Group 2.
Confidence Interval (round to 4 decimal places):
___< μ
1
- μ
2
<___
___
Answer for blank # 1:
2.6236
(50 %)
Answer for blank # 2:
7.1564
(50 %)
Hide question 17 feedback
Z-Critical Value = NORM.S.INV(.975) = 1.96
LL = (102.24 - 97.35) - 1.96 *5.98240+4.21240
UL = (102.24 - 97.35) + 1.96 *5.98240+4.21240
Question 18
1 / 1 point
A 2011 survey, by the Bureau of Labor Statistics, reported that 91% of Americans have
paid leave. In January 2012, a random survey of 1000 workers showed that 89% had
paid leave.
The resulting p-value is .0271; thus, the null hypothesis is rejected. It is concluded that
there has been a decrease in the proportion of people, who have paid leave from 2011
to January 2012.
What type of error is possible in this situation?
Type I Error
Standard Error
Margin of Error
Type II Error
No error was made
Question
19
1 / 1
point
Match the symbol with the correct phrase. µ
significance level
confidence level
parameter
power
P(Type II Error)
Hide question 19 feedback
This is a parameter of the population average.
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Question 20
1 / 1 point
A left-tailed z-test found a test statistic of z = -1.99. At a 5% level of significance, what
would the correct decision be?
Do not reject H
0
Do not reject H
1
Accept H
0
Reject H
1
Reject
H
0
Hide question 20 feedback
=NORM.S.DIST(-1.99,TRUE) = 0.023295468 < .05, Reject Ho.
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