Confidence Intervals

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candice01

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A study of 102 recruiters conducted by Execunet found that 77 did Internet research on candidates (data extracted from P. Kitchen, "Don't Let Any Digital Dirt Bury Your Job Prospects," Newsday, August 21, 2005. p. A59
a. Construct a 95% confidence interval estimate of the population proportion of recruiters who do Internet research on candidates.
b. Based on (a), is it correct to conclude that more than 70% of recruiters do Internet research on candidates?
c. Suppose that the study uses a sample size of 400 recruiters and 302 did Internet research on candidates. Construct a 95% interval estimate of the population proportion of recruiters who do Internet research on candidates.
d. Based on (c), is it correct to conclude that more than 70% of recruiters do Internet research on candidates?
e. Discuss the effect of sample size on your answers to (a) through (d).

Help please.

Thank you.
 


What is your question about this exercise? I mean, where are you stuck? What have you done thus far? Please be specific.

 
I'm not sure exactly how to figure out the confidence interval. Should I be multiplying 102 by .975 (95%) in order to get the confidence interval. How exactly do I determine the standard deviation with the few numbers that are provided? I did attempt part b. and 102 X 70% = 71.4 which would be above 70%.
 
candice01 said:
A study of 102 recruiters conducted by Execunet found that 77 did Internet research on candidates (data extracted from P. Kitchen, "Don't Let Any Digital Dirt Bury Your Job Prospects," Newsday, August 21, 2005. p. A59
a. Construct a 95% confidence interval estimate of the population proportion of recruiters who do Internet research on candidates.
b. Based on (a), is it correct to conclude that more than 70% of recruiters do Internet research on candidates?
c. Suppose that the study uses a sample size of 400 recruiters and 302 did Internet research on candidates. Construct a 95% interval estimate of the population proportion of recruiters who do Internet research on candidates.
d. Based on (c), is it correct to conclude that more than 70% of recruiters do Internet research on candidates?
e. Discuss the effect of sample size on your answers to (a) through (d).

Help please.

Thank you.
Click to expand...

What type of distribution are you expecting?

Did you consider "binary" distribution?

Any other thoughts?
 
I'm not sure possibly a student's t distribution, but I don't know how to get the 95% confidence interval estimate with just the two numbers given.
 
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