Is the water on your airline flight safe to drink? It is not feasible to analyze the water on every flight, so sampling is necessary. The Environmental Protection Agency (EPA) found bacterial contamination in water samples from the lavatories and galley water taps on 20 of 158 randomly selected U.S. flights. Alarmed by the data, the EPA ordered sanitation improvements, and then tested water samples again. In the second sample, bacterial contamination was found in 29 of 169 randomly sampled flights. Let 1 = proportion of flights with contaminated water in August and September 2004 and 2 = proportion of flights with contaminated water in November and December 2004.

(a-1) Choose the appropriate hypothesis and decision rule at = .05, using a left-tailed test.

a. H0: formula83.mml1 formula83.mml2 0 vs. H1: formula83.mml1 formula83.mml2 0

b. H0: formula83.mml1 formula83.mml2 0 vs. H1: formula83.mml1 formula83.mml2 = 0

c. H0: formula83.mml1 formula83.mml2 0 vs. H1: formula83.mml1 formula83.mml2 < 0

(a-2) Calculate the test statistic. (A negative value should be indicated by a minus sign. Round your answer to 4 decimal places.)

zcalc = ?

(a-3) Find the p-value. (Round your answer to 4 decimal places.)

p-value = ?