Background: This activity is based on the results of a recent study on the safety of airplane drinking water that was conducted by the U.S. Environmental Protection Agency (EPA). A study found that out of a random sample of 316 airplanes tested, 40 had coliform bacteria in the drinking water drawn from restrooms and kitchens. As a benchmark comparison, in 2003 the EPA found that about 3.5% of the U.S. population have coliform bacteria-infected drinking water. The question of interest is whether, based on the results of this study, we can conclude that drinking water on airplanes is more contaminated than drinking water in general.
Question 1: Let p be the proportion of contaminated drinking water in airplanes. Write down the appropriate null and alternative hypotheses.
Question 2: Based on the collected data, is it safe to use the z-test for p in this scenario? Explain.
Question 3: Now that we have established that it is safe to use the Z-test for p for our problem, go ahead and carry out the test. Paste the output below.
Question 4: What is the test statistic for this test? (Hint: Calculation already done by either technology option.) Interpret this value.
Question 5: What is the P-Value? Interpret what that means, and draw your conclusions. Assume significance level of 0.05.