Clickfraud has become a major concern as more and more companies advertise on the Internet. When Google places an ad for a company with its search results, the company pays a fee to Google each time someone clicks on the link. That’s fine when it’s a person who’s interested in buying a product or service, but not so good when it’s a computer program pretending to be a customer. Analysis of 1200 clicks coming into a business during a week identified 175 of these clicks as fraudulent.

Question

Clickfraud has become a major concern as more and more companies advertise on the Internet.  When Google places an ad for a company with its search results, the company pays a fee to Google each time someone clicks on the link.  That’s fine when it’s a person who’s interested in buying a product or service, but not so good when it’s a computer program pretending to be a customer. Analysis of 1200 clicks coming into a business during a week identified 175 of these clicks as fraudulent.
•	 What is the difference between a critical value and a test statistic?  How do you decide which test statistic to use?  
•	When is it appropriate to use a one-tailed test versus a two-tailed test?  Does the direction of the test affect statistical significance?  Explain. 
•	What is a P-value?  What does a P-value of 0.0000001 mean? 
•	What are degrees of freedom?  Illustrate with one new example. 
•	Under what conditions does it make sense to treat these 1200 clicks as a sample?  What would be the population? 
•	    Show the 95% confidence interval for the population proportion of fraudulent clicks in a form suitable for sharing with a nontechnical audience.         
Based on the scenario above, if a company pays Google $4.50 for each click, give a confidence interval (again, to presentation precision) for the mean costs due to fraud per click