Biology and Environmental Science Jet-engine emissions at high altitudes cause vapor trails that contribute to cloud cover and pollution, and may even affect weather patterns. An experiment was conducted to measure the concentration of volatile organic compounds (VOCs) directly behind an operating engine. A random sample of jet engines was obtained. The VOC concentration was measured (in mg/m3) before and after a special exhaust scrubber was installed. The data are given in the following table.
Use the sign test with a = 0.05 to determine whether there is any evidence that the median VOC concentration is smaller when the scrubber is installed. Find the p value associated with this test.