Question: When a colony of bacteria is subjected to strong ultraviolet light, they die as their DNA is destroyed. In a laboratory experiment it was found that the number of living bacteria decreased approximately exponentially with the length of time they were exposed to ultraviolet light. Suppose that 70.5% of the bacteria still survive after 7 seconds of exposure. What percentage will be alive after 30 seconds? How long does it take to kill 95% of the bacteria?