17 Stat questions for XXIAO

Daniel Kevins

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FOR XXIAO ONLY!!!!

 

 

Part 1 of 8 –

 
Question 1 of 17
 1.0 Points
Q-Mart is interested in comparing its male and female customers. Q-Mart would like to know if the amount of money spent by its female charge customers differs, on average, from the amount spent by its male charge customers.

To answer this question, an analyst collected random samples of 25 female customers and 22 male customers. Based on these samples, on average, the 25 women charge customers spent $102.23 and the 22 men charge customers spent $86.46. Moreover, the sample standard deviation of the amount charged by the 25 women was $93.393, and the sample standard deviation of the amount charged by the 22 men was $59.695.

Using the procedure advocated by Bluman,  at the 10% level of significance, is there sufficient evidence for Q-Mart to conclude that, on average, the amount spent by women charge customers differs from the amount spent by men charge customers.

 
 
 
 

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Question 2 of 17
 1.0 Points
An investor wants to compare the risks associated with two different stocks. One way to measure the risk of a given stock is to measure the variation in the stock’s daily price changes.

In an effort to test the claim that the variance in the daily stock price changes for stock 1 is different from the variance in the daily stock price changes for stock 2, the investor obtains a random sample of 21 daily price changes for stock 1 and 21 daily price changes for stock 2.

The summary statistics associated with these samples are: n1 = 21, s1 = .725, n2 = 21, s2 = .529. 

If you compute the test value by placing the larger variance in the numerator, at the .05 level of significance, would you conclude that the risks associated with these two stocks are different? 

 
 
 
 

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Question 3 of 17
 1.0 Points
Multiple myeloma or blood plasma cancer is characterized by increased blood vessel formulation in the bone marrow that is a prognostic factor in survival. One treatment approach used for multiple myeloma is stem cell transplantation with the patient’s own stem cells. The following data represent the bone marrow microvessel density for a sample of 7 patients who had a complete response to a stem cell transplant as measured by blood and urine tests. Two measurements were taken: the first immediately prior to the stem cell transplant, and the second at the time of the complete response.
 

Patient
1
2
3
4
5
6
7
Before
158
189
202
353
416
426
441
After
284
214
101
227
290
176
290

Suppose you wanted to conduct a test of hypothesis to determine if there is sufficient evidence to conclude that the mean bone marrow microvessel density is higher before the stem cell transplant than after the stem cell transplant?  What is the p-value associated with the test of hypothesis you would conduct? 

 
 
 
 

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Part 2 of 8 –
 
Question 4 of 17
 1.0 Points
A correlation value of zero indicates.

 
 
 
 

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Question 5 of 17
 1.0 Points
The marketing manager of a large supermarket chain would like to use shelf space to predict the sales of pet food. For a random sample of 12 similar stores, she gathered the following information regarding the shelf space, in feet, devoted to pet food and the weekly sales in hundreds of dollars. .
 
Store
1
2
3
4
5
6
Shelf Space
5
5
5
10
10
10
Weekly Sales
1.6
2.2
1.4
1.9
2.4
2.6
 
Store
7
8
9
10
11
12
Shelf Space
15
15
15
20
20
20
Weekly Sales
2.3
2.7
2.8
2.6
2.9
3.1

Compute the value of the sample correlation coefficient between weekly sales and shelf space.

 
 
 
 

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Question 6 of 17
 1.0 Points
In a simple linear regression analysis, the following sum of squares are produced:

f$sum{(y-ar{y})^{2}}f$= 500

f$sum{(y-y')^{2}}f$= 100

f$sum{(y'-ar{y})^{2}}f$= 400

The proportion of the variation in Y that is explained by the variation in X is:

 
 
 
 

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Question 7 of 17
 1.0 Points
Correlation is a summary measure that indicates:

 
 
 
 

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Question 8 of 17
 1.0 Points
The regression line y’ = -3 + 2.5 X has been fitted to the data points (28, 60), (20, 50), (10, 18), and (25, 55). The sum of the squared residuals will be:

 
 
 
 

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Part 3 of 8 –
 
Question 9 of 17
 2.0 Points
Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), “E” or “e” (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A survey of employees at a company finds that 32 of the 88 employees who drive to work were ever late during the past year, and 18 of the 64 employees who took public transportation were ever late during the past year.  At α = 0.10, is there a difference between the proportion of employees who drove who were ever late and the proportion of employees who took public transportation who were ever late?

Find the test value for the difference in the proportion of employees who were ever late for work in the past year.

Answer:

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