A web based software company is interested in estimating the proportion of individuals who use the Firefox browser. In a sample of 200 of individuals, 19 users stated that they used Firefox. Using this data, construct a 99% confidence interval for the proportion of all individuals that use Firefox.
a) What is the lower limit on the 99% confidence interval? Give your answer to three decimal places. Correct: 0.042.
b) What is the upper limit on the 99% confidence interval? Give your answer to three decimal places. Correct: 0.148
c) Google states that the proportion of all individuals that use Firefox is 0.2. Based on the interval above, does the Google claim seem reasonable? Correct: No because 0.2 is not inside the interval..
d) If you hadn't already taken the sample listed above, what sample size would be required so that the width of the 99% confidence interval would be at most 0.03 units wide? Be as conservative as possible with your answer!