Refer to the Computers & Security (July 2013) study of security issues with Microsoft products, Exercise 2.4. Recall that Microsoft periodically issues a Security Bulletin that reports the software affected by the vulnerability. In a sample of 50 bulletins issued in a recent year, 32 reported a security problem with Microsoft Windows.

a. Find a point estimate of the proportion of security bulletins issued that reported a problem with Windows during the year.

b. Find an interval estimate for the proportion, part a. Use a 90% confidence interval.

c. Practically interpret the confidence interval, part b. Your answer should begin with, “We are 90% confident ... “. d. Give a theoretical interpretation of the phrase “90% confident”.

Data from Exercise 2.4

The dominance of Microsoft in the computer software market has led to numerous malicious attacks (e.g., worms, viruses) on its programs. To help its users combat these problems, Microsoft periodically issues a Security Bulletin that reports the software affected by the vulnerability. In Computers & Security (July 2013), researchers focused on reported security issues with three Microsoft products: Office, Windows, and Explorer. In a sample of 50 security bulletins issued in 2012, 32 reported a security issue with Windows, 6 with Explorer, and 12 with Office. The researchers also categorized the security bulletins according to the expected repercussion of the vulnerability. Categories were Denial of service, Information disclosure, Remote code execution, Spoofing, and Privilege elevation. Suppose that of the 50 bulletins sampled, the following numbers of bulletins were classified into each respective category: 6, 8, 22, 3, 11.