I need some explanations as well please Bob is doing a resea

I need some explanations as well please.

Bob is doing a research project to determine the proportion of Yale University students who favor capital punishment. If no preliminary sample of students is taken, how large a sample is necessary to be 99% sure that a point estimate will be within a distance of +/-1 percent (E)?

A. 16641

B. 14718

C. a sample of greater than 30

D. None of the above

The slope of a regression equation is 10, the value where the line intersects the Y axis when X = 0 is 4. What is the regression equation?

A.X = 0 + 10Y

B.Y = 10- 4X

C.Y = 4 + lOX

D.Y = 4- lOX

E.none of the above

If everyone paid taxes equal to 10 percent of their total annual income, the value of correlation coefficient for income and taxes would be nearest to

A. 0.00

B. -1.00

C. 1.00

D. None of the above

Director of a company wants to know the mean salary of the company’s employees. The most effective way to determining this is to

A. Record the salaries of a simple random sample of employees

B.Record the salaries of a stratified random sample of employees

C.Record the salaries of a cluster random sample of employees

D.Record the salaries of a convenience sample of employees

E. Consult computer records regarding the salaries of all employees.

A researcher theorizes that first-born children of African-American families are more intelligent than other African-American children. A sample of 50 first-born children of African-American families is found to have an average IQ of 105, while based on other studies we can assume that IQ of other African-American children is 100 on average and has standard deviation of 15. What is the population of interest in this study?

A. All african american families

B. All african american children

C. IQ of all african american children

D. IQ of all first born african american children

A researcher is interested in studying the perceived life satisfaction among younger adults and hypothesizes that life satisfaction among younger adults is different than the general public. She did a pilot study and gave a life satisfaction test (known to have high reliability and validity) to nine younger adults (between 20 and 30). Scores on the measure range from 0 to 5 with 5 indicative of high life satisfaction, and 0 indicative of no life satisfaction. The collected data is: 4, 3, 3, 4, 5, 2, 2, 2, 2 ... Assuming life satisfaction of 2.5 for general public, conduct the appropriate test and answer the questions. What is your t critical value (calculated t value)?

A. -1.6

B. +1.3

C. +2.1

D. +1.8

Solution

1.

Note that      
      
n = z(alpha/2)^2 p (1 - p) / E^2      
      
where      
      
alpha/2 =    0.005  
As there is no previous estimate for p, we set p = 0.5.      
      
Using a table/technology,      
      
z(alpha/2) =    2.58  
      
Also,      
      
E =    0.01  
p =    0.5  
      
Thus,      
      
n =    16641  
      
Rounding up,      
      
n =    16641   [ANSWER, OPTION A]

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