The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. They argue that early detection is not more likely because over 50% (say 60%) of the detectors are inoperative now. But this assumes the extra 15% of homes with detectors does not outweigh this. What if MORE than 50% of detectors were inoperative (80%) 10 years ago. Since that time, we went from 80% to 60%, and therefore even though 50% of the detectors are inoperative, there were far more inoperative 10 years ago than now. Because of this, an additional 15% of homes with detectors does indicate an increase in early detection. This is why for the argument to work the percent of inoperative detectors 10 years ago must be LESS than 50%. This is AC D.
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The National Association of Fire Fighters says that 45 percent of homes now have smoke detectors, whereas only 30 percent of homes had them 10 years ago. They argue that early detection is not more likely because over 50% (say 60%) of the detectors are inoperative now. But this assumes the extra 15% of homes with detectors does not outweigh this. What if MORE than 50% of detectors were inoperative (80%) 10 years ago. Since that time, we went from 80% to 60%, and therefore even though 50% of the detectors are inoperative, there were far more inoperative 10 years ago than now. Because of this, an additional 15% of homes with detectors does indicate an increase in early detection. This is why for the argument to work the percent of inoperative detectors 10 years ago must be LESS than 50%. This is AC D.