Chris drank a cup of coffee with 150 milligrams of caffeine. Each hour the caffeine in Chris' body diminishes by about 9%. How long after the coffee is consumed will it take for the caffeine in Chris' system to drop below 25 mg? Round your answer to the nearest hour.
So for this problem, we can simply subtract 9% of the caffeine left in Chris' body repeatedly until we get below 25 and count up how many times we had to subtract.
